heavier springs do allow the tappet to resist pump up. like anything else there's pros and cons to heavier springs.

I think the .020"-.040" thing came out of the mid to late '60's. I remember the chevy guys reducing their tappet pre-load by backing off the rocker. I don't think any of us back then truly understood pre-load; we were just trying to get more rpm by eliminating pump-up. a lot of the hobby is monkey see-monkey do so the ford and mopar guys thought they had to do the same thing; me included. I can't say that I gained much, if anything, by doing this. if I remember correctly valve spring changes meant more than tappet adjustments. now I just put the plunger somewhere around mid travel and just let the juice lifter be what it is.