I just picked up Boice's commentaries and EBC (old school version) mainly just to replace dead tree versions with Logos ones.  It got me thinking, just how many commentaries are enough?  I generally use about 4 or 5 and have others that are more technical or specialized for difficult texts.  After adding these two to my Logos Library, I probably will not buy any more sets, just individual volumes here and there.  I guess it only took me 10 years to get all of the ones I want in Logos, but it made me wonder how many everyone else uses on average and if they will buy more just to have more in Logos?