If I understand the rules correctly partisan units can't appear anywhere within 5 hexes of a unit but with the different scales between wpe and wpp shouldn't that be more like 2 or 3 hexes in wpp? if you play China 37 scenario partisans are a huge problem but in the regular game they rarely appear?
I had railroad breakdowns very frequently in China 37 despite how I put divisions at regular intervals all over the Chinese region that could move about to affected areas while still keeping the general network secured but still many breakdowns. I couldn't get supply most turns to over half of my units in China cause of rail breaks mostly I think.