Just my personal opinion, but I actually think it’s bad practice to use very long chains of plugins except in exceptional circumstances, both from the audio quality point of view and in pure practical terms. Something like this is easy to ask for but it might be worth thinking it through from A to Z. It certainly wouldn’t be easy to access/manage 25 slots in the master section. You’d probably be doing a lot of scrolling unless the slots were displayed on screen in a different manner.
However, if more inserts were added to the forthcoming WL10 master section I wouldn’t complain (but I’d rarely use them since 12 is enough for me). If ever I need more (for some exceptional circumstance) I’m perfectly happy using Blue Cat’s PatchWork.
Each to their own way of working of course.