I have a Pro project document that I am using to do some data processing using a notebook script and one map with references to file geodatabases, a bit of SDE and some feature services, including imagery. When I first packaged it up it took about 5 hours (though for some reason it is not counting correctly, because it somehow is missing the gathering part that seems to take forever). That was long but not unbearable, though I expected a larger file than 94.584 MB.

Then I went over to another project that was less complex and it took minutes not hours to create the package. This one also has a lot of varied sources and about 30 maps.
Then I went back to the first one a week later, and Project Package took about 12 hours.
So, in general terms, what is it doing for the gathering, what optimization can be done to get through it faster?