I may be more convinced than you are about McV's general approach and less convinced than many are about the application to the OL.
I like McV's approach to preparing vets. McV grew up in Walsh's orbit at SF, and that brilliant coach pretty much proved that training camp and preseason games should not be the traditional grind. I like that approach, especially with our vets. Goff. Gurley. Whit. Talib. These guys don't need much game action to get up to speed. They need to be prepared well for the games, but I am happy to see them spared any jeopardy.
Knock the rust off? Maybe a little. Marshall used to say he needed 3-4 carries and he would be good. 'Course, he was Marshall. But if there is such a thing as rust for vets, I don't see it as much of a factor. Put them in baseball caps on the bench.
I feel very differently about green players who need to LEARN. Obviously, cases will vary according to talent level and position. Some positions have a longer learning curve than others do.
And OL ... Man. Talk about a learning curve ...
Think of what Allen is facing. As I say, I like everything I know about the guy. I know he's working his tail off preparing. But he is about to face the responsibility of not only blocking but also making calls dealing with the bewildering complexity of NFL defensive fronts. No matter how well prepared he is in the film room and in drills, it is going to take time for him to get things in hand facing live stunts, blitzes, and all the rest. You can't just take the film room onto the field if you haven't faced the wrath of DCs preparing fiendishly to disrupt our high powered offense.
Of course, 6 PS quarters wouldn't get him there either. But he would have a lot more chances to face and deal with NFL fronts than practices and scrimmages could give him.
Or, at least, I can't see how that isn't true. I just cannot sign on to the Kromer/McV theory for NB and Allen. They may well prove me wrong. I hope they do. But I am not convinced.