This thread is not boring at all and is very important.

I think the best PFR strategy takes into account the # of limpers the starting hand your table image, the aggressiveness of your opponents, the stack sizes, and some random element.

In short there is no simple formula or rule. Just many thousands of hands of experience.

Typically 3-6 BB is my range with 4 being my standard EP (checked to) bet. If I see I'm getting too much action I'll step it up to 6 for a while.

My overall game relies on good post-flop play so I don't mind action. If you are getting chewed up post-flop, step up the PFRs, you should get less action and be better prepared for post-flop play.