I can see why someone would hate locking to the baseline grids. Especially since the last row of the page moving up and down by a few pt on every page really doesn’t matter much on printed books, as with the bending paper pages and small type it’s more or less unnoticeable.

When I see that happen on PDF ebooks, however, it drives me absolutely crazy and feels so amateurish that I basically gag each time I turn a page. So lately I’ve ended up using the baseline grid for body and the first lines of headings, but lowering the baselines of headings to roughly match the ascender to that of the body text for perfect spacing between the heading and the body, and to align the headings with the body when they occur at the top of the page.

My latest job was a scientific book with lots of indented quotes, three levels of headings, and references at the bottom of roughly two thirds of the pages. The references had a rule above them, which made the wandering bottom row really noticeable. The layout was a trainwreck until I switched locking to baseline grid on. It took a lot of careful adjusting to get right, but after that was done, the book flowed through quite beautifully, requiring only a few manual adjustments before I sent it off.