I also believe reparations should have been based on a case-by-case basis simply because each case was probably different in one way or another.
Ideally, yes. In practice, given the number of cases, that's too impractical:
5 years later in 1988 the Civil Liberties Act came in to force and Congress backed reparation payments of $20,000 to each living survivor (or next of kin) along with a signed apology from the then US President Ronald Reagan. A total of around 82,000 people received payments.
Governments tend to deal in cold hard numbers. They will have committed a certain amount to reparations. Any investigations into the merits of each case would likely have come out of that $20k per person. The most efficient way to deal with it is same amount per person, and then process any appeals later if there aren't too many.
That is all about logistics and dollars, though. It won't bring back the dead or heal ruined lives. The best reparation that can be made is to learn the lesson about why it occurred, and prevent it from ever happening again. My last post with that huge list of racially motivated crimes influenced by Trump may not appear to be relevant to the discussion, but actually it is absolutely central.
If you imprison people from a racial motivation in the 1940s, then say sorry and pay compensation in the 1980s, and then another forty years later we have a president who is actively encouraging racial division, then no lessons have been learned. If the government aren't reining Trump in, then they are complicit.
If you punch someone in the face, then say sorry and give them a dollar, then punch someone else in the face a couple of minutes later, then the apology and the compensation look kind of meaningless.