Optaplanner Construction Heuristics Phase Unique ValueRange - optaplanner

Question

I am working on optimizing the Construction Heuristics for the solution domain
I have a ValueRangerProvider as the following.
#ValueRangeProvider(id = "timeRange")
public CountableValueRange<LocalDateTime> timeRange() {
final LocalDateTime start = LocalDateTime.now().plusHours(1).truncatedTo(ChronoUnit.HOURS);
final LocalDateTime end = LocalDateTime.now().plusYears(1).truncatedTo(ChronoUnit.HOURS);
return Stream.iterate(start, d -> d.plusHours(1))
.takeWhile(localDateTime -> localDateTime.isBefore(end))
.collect(Collectors.toList());
}
This #ValueRangeProvider provides LocalDateTime instances for every hour between the start and end to be used in a Time Grain model. The timeRange value range is the only #PlannningVariable in the #PlanningEntity class.
I also have a following solverConfig.xml:
<?xml version="1.0" encoding="UTF-8"?>
<solver xmlns="https://www.optaplanner.org/xsd/solver" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://www.optaplanner.org/xsd/solver/solver.xsd">
<scanAnnotatedClasses/>
<scoreDirectorFactory>
<constraintProviderClass>org.acme.optaplanner.solver.MyConstraintProvider</constraintProviderClass>
<initializingScoreTrend>ONLY_DOWN</initializingScoreTrend>
</scoreDirectorFactory>
<termination>
<bestScoreFeasible>true</bestScoreFeasible>
</termination>
<constructionHeuristic>
<constructionHeuristicType>FIRST_FIT</constructionHeuristicType>
<changeMoveSelector>
<selectionOrder>ORIGINAL</selectionOrder>
</changeMoveSelector>
<constructionHeuristic>
</solver>
During the Construction Heuristics, the objects initialization is more important than the quality of the solution. Given there is enough time slot that no hard constraint can occur.
I realized that the #ValueRangeProvider(id = "timeRange") values used by the previous steps are being re-used in the later steps during the Construction Heuristics.
1772 [main] DEBUG o.o.c.i.c.DefaultConstructionHeuristicPhase - CH step (0), time spent (157), score (-999init/0hard/-1soft), selected move count (1), picked move (Lesson{id=1, subject='Math I', pinned=false, startTime=null, durationInGrains=3} {null -> 2020-09-27T09:00}).
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02:01:26.494 [main ] DEBUG CH step (497), time spent (14513), score (-502init/0hard/-5542soft), selected move count (664), picked move (Lesson{id=498, subject='Math I', pinned=false, startTime=null, durationInGrains=3} {null -> 2020-11-10T12:00}).
02:01:26.565 [main ] DEBUG CH step (498), time spent (14584), score (-501init/0hard/-5548soft), selected move count (666), picked move (Lesson{id=499, subject='Math I', pinned=false, startTime=null, durationInGrains=1} {null -> 2020-11-10T14:00}).
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17456 [main] TRACE o.o.c.i.c.d.ConstructionHeuristicDecider - Move index (0), score (-500init/-2hard/-5571soft), move (Lesson{id=500, subject='Math I', pinned=false, startTime=null, durationInGrains=2} {null -> 2020-09-27T09:00}).
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02:01:26.637 [main ] DEBUG CH step (499), time spent (14656), score (-500init/0hard/-5557soft), selected move count (667), picked move (Lesson{id=500, subject='Math I', pinned=false, startTime=null, durationInGrains=2} {null -> 2020-11-10T15:00}).
02:01:26.711 [main ] DEBUG CH step (500), time spent (14730), score (-499init/0hard/-5568soft), selected move count (668), picked move (Lesson{id=501, subject='Math I', pinned=false, startTime=null, durationInGrains=3} {null -> 2020-11-10T16:00}).
02:01:26.787 [main ] DEBUG CH step (501), time spent (14806), score (-498init/0hard/-5581soft), selected move count (670), picked move (Lesson{id=502, subject='Math I', pinned=false, startTime=null, durationInGrains=1} {null -> 2020-11-10T18:00}).
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02:17:46.156 [main ] INFO Construction Heuristic phase (0) ended: time spent (98518), best score (0hard/-11165soft), score calculation speed (6783/sec), step total (1000).
02:17:46.165 [main ] INFO Solving ended: time spent (98527), best score (0hard/-11165soft), score calculation speed (6776/sec), phase total (2), environment mode (NON_REPRODUCIBLE).
The LocalDateTime of 2020-10-01T09:00 was used in the CH step(0) and CH step(499).
Since I have a hard constraint that constrains that two #PlanningEntity cannot use the same timeRange value I was wondering if the used timeRange value can be removed for future steps to use?
As an example;
I have changed the constructionHeuristic configuration
<constructionHeuristic>
<constructionHeuristicType>FIRST_FIT</constructionHeuristicType>
<changeMoveSelector>
<selectionOrder>RANDOM</selectionOrder>
</changeMoveSelector>
<forager>
<pickEarlyType>FIRST_FEASIBLE_SCORE_OR_NON_DETERIORATING_HARD</pickEarlyType>
</forager>
</constructionHeuristic>
Which lead to a much fast Construction Heuristics performance because the step was choosing #Planningvariables for #PlanningRangeProvider at random.
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2535 [main] TRACE o.o.c.i.c.d.ConstructionHeuristicDecider - Move index (0), score (-2init/0hard/-3303soft), move (Lesson{id=998, subject='Math I', pinned=false, startTime=null, durationInGrains=2} {null -> 2020-10-13T20:00}).
2535 [main] DEBUG o.o.c.i.c.DefaultConstructionHeuristicPhase - CH step (997), time spent (1046), score (-2init/0hard/-3303soft), selected move count (1), picked move (Lesson{id=998, subject='Math I', pinned=false, startTime=null, durationInGrains=2} {null -> 2020-10-13T20:00}).
2536 [main] TRACE o.o.c.i.c.d.ConstructionHeuristicDecider - Move index (0), score (-1init/0hard/-3312soft), move (Lesson{id=999, subject='Math I', pinned=false, startTime=null, durationInGrains=3} {null -> 2021-08-26T22:00}).
2536 [main] DEBUG o.o.c.i.c.DefaultConstructionHeuristicPhase - CH step (998), time spent (1047), score (-1init/0hard/-3312soft), selected move count (1), picked move (Lesson{id=999, subject='Math I', pinned=false, startTime=null, durationInGrains=3} {null -> 2021-08-26T22:00}).
2537 [main] TRACE o.o.c.i.c.d.ConstructionHeuristicDecider - Move index (0), score (0hard/-3317soft), move (Lesson{id=1000, subject='Math I', pinned=false, startTime=null, durationInGrains=1} {null -> 2021-03-10T15:00}).
2537 [main] DEBUG o.o.c.i.c.DefaultConstructionHeuristicPhase - CH step (999), time spent (1048), score (0hard/-3317soft), selected move count (1), picked move (Lesson{id=1000, subject='Math I', pinned=false, startTime=null, durationInGrains=1} {null -> 2021-03-10T15:00}).
2540 [main] INFO o.o.c.i.c.DefaultConstructionHeuristicPhase - Construction Heuristic phase (0) ended: time spent (1051), best score (0hard/-3317soft), score calculation speed (1304/sec), step total (1000).
2549 [main] INFO o.o.core.impl.solver.DefaultSolver - Solving ended: time spent (1059), best score (0hard/-3317soft), score calculation speed (1169/sec), phase total (2), environment mode (NON_REPRODUCIBLE).
Is there a sufficient way to restrict steps from using pre-used value ranges? Would there be any draw backs?