Me personally, that I have used as 'primary phones', NOT counting warranty replacements as separate phones, I am at "sort of 5."
My whole in-house family, not counting warranty replacements, is at 6. I put "sort of 5" because of the six that "anyone in the house" has used, I have at some point used 5 of them.
Whole family listing, by order of purchase:
iPhone (original/2G) bought on launch day. Replaced by Apple as "battery replacement"
iPhone 3G bought on launch day. Replaced by Apple under warranty.
iPhone (original/2G) bought used from a friend on 3G launch day
iPhone 3G bought refurbished
iPhone 4S bought on launch day
iPhone 4 bought used
Usage:
- iPhone (8 GB): Bought on launch day, I used it, then passed to my son on 3G launch day. He used it until he killed it and upgraded to a 3GS.
- iPhone (8 GB): bought on launch day by a friend; he sold it to me on 3G launch day for use by my wife. Then she lost it, then it was found, it got replaced ("battery replacement" by Apple for $70 got a like-new replacement,) then my daughter used it, and I'm using it right now as my primary personal phone.
- iPhone 3G (white, 16 GB): bought on launch day, used by me. Then passed to my wife, then to my daughter, currently unused.
- iPhone 3G (black, 8 GB): bought refurbished when 3G was still the current model. Used by my wife, then my daughter, currently unused.
- iPhone 4 (black, 8 GB): bought used when the 4S was current model. Used by my wife, then by me as my 'personal phone' after work provided me with a 5C, now by my daughter.
- iPhone 4S (white, 16 GB): bought on launch day, used by me, then passed to my wife when work provided me with an iPhone 5C, and I traded down to her iPhone 4.
The only one I have never used as a primary device was my wife's 'bought refurbished' black iPhone 3G, which currently has a cracked screen. I have Whited00r and iDroid loaded on it, just for fun. Everything else I have used as my primary personal phone for some period of time.
My downgrade of my personal phone from 4S to 4 to original was because my work provided me with a 5C. When I first got it, our device management system was
strict, with very few third-party apps allowed, and lots of the built-in functionality disabled (Siri, nearly all iCloud functions, the ability to connect to a computer to load music/videos, FaceTime.) So I still wanted to have a personal phone to do those on. So I took my wife's 4 and gave her my 4S. Then a few months later, work "unlocked" our work iPhones, allowing nearly everything (instead of a "whitelisted custom app store," we have access to the full app store with only a few apps blacklisted; and iCloud document storage is blocked, but all other iCloud functionality is enabled, as well as Siri and FaceTime.) Since I can now use my work phone for nearly all "smartphone" usage, I passed the 4 to my daughter to replace her aging 3G, and since the only thing I use my personal phone for is any more is phone calls and text messages, I decided for nostalgia's sake to use the original iPhone. (I'm actually tempted to find an old Motorola SLVR L7 and use that, if I can find a T-Mobile-compatible one with iTunes support.)