I do not think time is the major variable. The significant element is how unknown the identity of the grave resident is- for example, it will likely never be possible to loot the grave of Lincoln Tomb without objection because its contents are well recorded. On the other hand, if there is an unmarked grave exhumed for the purpose of identifying the dead person it is possible for that to be acceptable. Time is a factor in determining the progress, but not the key quality.
Also the intentions of the person doing the digging. For personal profit vs academic study.
UN: Epicyon
Also the intentions of the person doing the digging. For personal profit vs academic study.