My philosophy has changed many times over the years, but it's been settled in one direction for the last four or five:

Shrink my collection to less "manual of arms" and only have a two copies on a single top-of-the-line gun. The days of 5 copies of a single design are over.

My collection is settling out to be:

(2) Ruger Mk3
(2) Ruger 10/22 Stainless Carbine with Leupold Scopes
(2) Ruger 10/22 Stainless Takedown with Tech Sights
(2) Ruger LCP
(2) Glock 19
(2) Glock 26
(2) S&W Shield 9
(2) 1911 (Les Baer Stainless Custom Carry and Ed Brown Executive Elite)
(2) HK 45Acp
(2) FN Scar-16 with ACOG
(2) FN Scar-17 with ACOG
(2) Springfield Armory SAR-48
(2) Benelli M1 Super 90

Why two? One in use and one in reserve. The reserve is tested and placed in tr safe but available for duty should the primary go down. The primary gets replaced or repaired as necessary. If the primary wears out - a new replacement is bought / tested and becomes the reserve. Gear rotation.

I'm getting close to being down to this collection. I have (3) Rem 870, a couple of ARs, (2) Marlin 22WMR, (1) LCP, (1) Ruger Mk3, several 10/22, and (1) Scar to sell and I'll have my perfect collection.