Backfilling is overhyped, IMHO. DHEA more than Preg, can be not well tolerated in a lot of guys, aromatases easily, etc. But like all of this some love DHEA, some love Preg, and some like me avoid it entirely. There are no negatives to not supplementing...it's like one of these things that (IMHO) it's treating a number on a lab page vs is it really necessary to do it.
I know we have many threads on back filling the pathways, but many members cannot deal with the HCG and DHEA because of estrogen levels or sleep issues. I think back filling is a very individual thing, I do supplement with 25 mg of DHEA daily and 500 IU of HCG every 3 1/2 days. But that's me.