Neither of us is right or wrong, it's just that the possibility exists that an incorrect adjustment could be made. You've never had a problem, that's a good thing. I have seen the problem occur, just once or twice, and readjusting the rocker took care of it. In the instances where there was a problem the initial setting was done with the engine not running and the readjustment was done with the engine running (back it off until it clatters, slowly tighten until until it's quiet, and slowly add another 3/8 turn). In the case of installing new lifters, Crane and others recommend that you don't fill the lifter with oil before installation and the setting of preload for that reason. Now that we've thoroughly confused Rolandag2....
I pumped my lifters up per the advice of my mechanic who assembled my engine. We then adjusted the valve train ('66 heads). So was it a mistake to do it that way? Am I gonna have problems?...
If the valves adjusted ok you're not gonna have any problems. It's just that when a lifter is sometimes pumped up it can take longer to bleed and make the adjustment correctly. It can be easier and quicker just to not have oil in them to start with. Some guys try to do the job too quickly, don't get the adjustment right, then hear a tapping noise after they get the valve covers back on. The only "problem" it causes is you gotta readjust it. That could be time better off spent drinking a beer or two.