When is a Project(.APRX) too big?

[graharg_MAO]

When is an ArcGIS PRO Project too big?  What is your practice on managing the theme, complexity, connections and purpose of project files?  I have practiced limiting my projects to themes and AOIs but Then I end up with many projects with few maps and a few projects with many maps.  I am sure there are limitations, but I have not hit many.  When the project gets slow or off subject I start a new project.

One measure is the size of the Display Cache.  I do clear the cache regularly when performance becomes an issue .  I also frequently clear the %TEMP%  

[KeithAddison1]

I found this thread while researching a problem I'm having with a large .aprx file in Pro 3.3.  It has 25 layout tabs, and one map tab with about 100 layers, about 3/4s of them are vector, rest are raster some quite large (to about 2GB).  This aprx appears to have become bugged/defective: it can no longer export the georeferencing properly.  Nothing can read the world files it makes (and presumably the formats I've tested that write the reference into the file itself) Exports fine from a smaller aprx.  Lag isn't much of a problem with this large aprx, and the aprx file size on disk is only 3.2 MB.  But the georeferncing issue is a show stopper.  I can't really fix the exported raters after the fact, the exported rasters aren't just correctly located with no defined projection - its just plain wrong and the only fix would be manually georefernce it back via control points.  Currently I'm attempting to drop it all into a new aprx to see if I get the exact same problem - wondering if this bug I'm getting is stochastic or deterministic, if the later then I'll report it.  EDIT: I get the same problem with a totally fresh aprx, georef for tiffs is totally unworkable.