I am not aware of a limit either, but I have noticed that the Crop to Roof tool which was being quietly buried has made a bit of a comeback in the menu structure. This suggests GS are trying to reduce the number of SEO calculations, perhaps to provide more processing capacity for the new Opening tool.
Apple iMac macOS Big Sur / AC24UKI (most recent builds)
As pointed out already: 'best practice' is to use it wisely.
Don't use SEO on elements that do not even intersect by selecting a whole lot of elements to interact with some other elements, without checking if they actually intersect.
With building materials making automatic connections in most cases and merge/connect solving most others, there is very little need for SEO except for sloped roof connections with walls, in my experience.