My modules keep at rather steady 80 - 90. I do hoard PP modules, but I foolishly got too few of many of them the first when I first went through the Powers and now have to do a second round for the ones I really like. For ships I tend to keep a static build once it's 'finished' and not change it unless I'm radically altering the ship's purpose. I also don't get too attached to my engineered modules because I have been thinking I can easily always engineer more. Recently I have been engineering a number of ships in rapid succession and am actually having some material shortages. I barely remember the last time I had that problem.