You can farm blue barb helms faster than you can farm pgems.
Even if you had unlimited pgems, the value vs reroll results are so miserable that even if a bot could accomplish this task super fast, that would still be a suboptimal waste of time/resources.
Even charms are not worth rerolling anymore since the introduction of TZs.
I would advise you to not waste time cubing flawless gems into pgems, unless you want to craft. And this would often mean only targeting :
Saphire for kb gloves
Ruby for blood rings/gloves/helms/belts
Amethyst for caster amys/boots
Ideally only 1 type so you save time looting directly into cube instead of moving all that crap around nonstop.
One could argue that pskulls are still worth it. To reroll rares.
I was advocating in that direction for a while. But I don’t even believe in that anymore, due to the fact that you can’t reroll eth items, and that other things like diadems are much more efficiently gambled anyway.
You may ignore all the above if you do not care about efficiency and you just want to have some casual diversified gaming experience with a feeling of looting stuff for fun.
May luck/RNG be in your favor
D2:R