Interesting. Yes, my Rapid Fixer had the wrong directions (or rather, only paper directions) but I downloaded the documents from Ilford's website when I was first mixing up all my chems.
My Paterson tank is actually my best. It has a good rubber lid to do inversions. I haven't been inverting though, because all the instructions I've read don't say to. My agitation consists of spinning the reels twice, then crisply sliding the tank forward and aft a few times, then left and right a few times, then spinning the reels again twice. Usually about 15 seconds of agitation total.