If you were happy with your new plane why did you spend 4 1/4 hours on it?
I think you are getting worked up ot something that Was never that much of an issue until companies like Lie Neilsen used it as a sales tool and engineers became interested in woodworking as a hobby.
The only time people flattened soles in the old days was for a really worn mouth. Otherwise, most of the planes now on the used tool market were never flattened by their original owners and they managed to do good wok with them. My mentors only had me take sandpaper to soles to get the rust off and make them easier to push.
My best 4 1/4 smoother from 1920 has never been flattened and does great work, even if it does have a minor hollow behind the blade. There is no need to flatten soles if the plane works well, and planes move, anyway.
Everyone has watched Paul’s tutorials on flattening soles, but I think even he thinks there is a bit too much focus on that and not enough on more important aspects.
Here is post Paul did a while back in an introduction to his plane flattening tutorial that gives his views on how important it is. The words “mostly flat” are key .