Well I was thinking I would get a new phone for Christmas and maybe keeping my old phone as an I nternet radio for the bed room with some computer speakers.
I'll sometimes carry 2 phones I like to keep two active devices around.
The phones I don't currently use go back into their original boxes.
If the items sit for 4-6 months I'll usually dispose of them.
I have 4 phones now...2 are back in their boxes in a drawer.
Unless I can find a specific reason to keep the old phone like giving it to a family member or get rid of them online; I see little purpose to keep them.
I use a 1020 as my daily driver (running Windows Phone 8.1 Update 1), together with my Asus Nexus 7 (2013).
My 920 is being used to test the Windows 10 Mobile Technical Preview (and also to run any future apps I develop) !