My interest in the recent past was dictated by space... I have my own rifle & pistol range, & was collecting rifles at a much greater rate... then I came to the realization that 4 safes & a couple lock boxes & crates wasn't the most practical method of storing them... since I already had stuff stashed in safes, lock boxes & crates... I built a walk in gun safe room, intentionally large enough to put my reloading bench, & all my components, & Mrs. jewelry & our documents, since it's fire proof as well...
trouble is, I had more long guns than I thought, & I had wanted to display everything on the walls in the safe room, from the start... I wasn't even able to get everything moved in, before I ran out of room... so for a while traded off long guns & bought more handguns, just because they take up less room, or I traded off a whole model of shotgun collection for one higher end rifle, to condense...
now I have things grouped, & have a couple of spots for specific guns ( either long guns or handguns ) anything other than those specific pieces "needed" it now requires trading off an existing gun to make room for something different...