If you roll 1d6 and reroll 1's until you get something else, you'll have a result of 2, 3, 4, 5, or 6, with equal chances - which is the same as rolling 1d5+1, without any rerolls.
If you roll this 4 times and keep the highest 3, then you have 1d5+1, 1d5+1, 1d5+1, 1d5+1, keep highest 3. The +1 is fixed, so this is the same as rolling 4d5, keep 3 highest, plus the three +1's with the 3 highest rolls - which is the same as
4d5+3, keep 3 highest d5's. Without any rerolls.
Any thoughts or feelings about this?