doing PI is all about doing it on the right place, highsec is a waste of time, same as hi-lowsec. only .1 low sec, or null will give you good yields. WHs are fantastic, but the logistics will drive you crazy.

i had for a long time a massive multiboxed pi chain. and yes, as said above me all you need to do is get the command centers down (anywhere on the planet, no need to sync this), then use the "->" button to center all the windows on the CC, and drop everything.

the limiting factor is that all characters need to have the same number of planets (lets call them "slots") and any given slot has to have the same production across all characters. (otherwise the pick up logistics are a pain) you can multibox, both the cycle refreshing, and the material pick-up this way. and in 10 minutes refresh an entire 100+ planet setup across multiple sets of characters.

i had all characters 1-10 do p2 materials on slots 1-5 then 6th slot was for overflow. (extracting whichever material i was low on) then everything was moved to the 11th character who grinded the stuff down to p3 - p4. everything in one wormhole, once a month i cashed out about 13+b in pi poo. i remember making an absurd amount of money initially, by simply making coolant. (p2)

your forte is being able to refresh cycles on a massive scale of planets in a short amount of time, so play on it, use short cycles. Wormholes are the best, specially C4. C3 are high transit, and C5 are all taken. short cycles have higher extraction rates over long cycles, on WHs this higher efficiency is SO crazy that my planets ended up having only one extractor and the rest factories, since i simply couldn't keep up with the extraction.

once a week empty the POCOs for the extractors, and once a month use you grind character to mash everything down, using a bunch of factory planets. (nothing but factories on the planets, no extractors)

should one of your planets have low yield, don't fix it manually, it doesn't matter. one of the other characters will cover the gap until the resource patches move around on their own.