There is the idea of commensurate punishment. 20 years for destroying evidence for something that while serious didn’t defraud anyone, maim anyone or cause damage I think is unreasonable and unconstitutional.
20 year is the absolute maximum for the worst evidence tampering you can think of. A serial offender, after knowingly and willingly leveling a city block with people in there the second time to hide his street gang’s accounting fraud, and exhibiting open contempt towards the judge while loudly proclaiming he will do it again after they let him out. That person can not get more than 20 years for the specific crime of evidence tampering. That is what the 20 years statutory maximum is.