I've been using Linux full time since 2007.
As to the question, I guess in a sense you could say I've been using the same distro continuously. I multi-boot so I always have 5-8 distros on my hard drives at any given time. I started with PcLinux back in the old Kde3 days and used it pretty much exclusively, then had a few issues around 2010 and went to Slackware as my primary OS. I still use PcLinux as my anchor system as it seems the only distro still using Grub legacy which I prefer and because it was the distro that introduced me to Linux.
I will say if there was no Slackware i would still probably use PcLinux as my everyday system as it does have a lot going for it, but Slackware is and probably will remain my main OS for the foreseeable future. Unless of course they go to systemd, then I guess I'll be forced to learn Bsd.

Centos

Slackware - 9 years so far. There are other distros?

When I get pissed off I move on. Sometimes takes a while - sometimes not. Sometimes I come back - sometimes not.

I'm more interested in the kernel itself (i.e. *Linux"*) than the wrappings. However all developers (including the kernel devs) make some stupid decisions. Then it's "refer to first sentence".

I've had a Slackware install since around the time I joined. I keep a dedicated partition for other distros I want to try out for trivial reasons: newer DE and other things I don't really care to have on my Slack installs enough to bother with.

I did the usual move from one distro to the other at first and settled on Kubuntu for my desktop until Canonical did something annoying and I decided to give Debian a shot. A few years ago I moved my EEEPC from Mint to Debian also and my Pi runs Raspbian. So as things stand I've been using Debian on my desktop for at least 5 years and my EEE for I'd say at least 3.
However, I do keep playing with Slackware and have dual-booted now and again. So if I find there's a change to Debian I don't like that's likely where I'll jump ship to.
I also like to play with a few distro's in VirtualBox to get an idea of what's out there, pick up ideas and the like.

I stuck with Mandrake for about 4 years; since then for my desktops and dev stations I've always seemed to use Ubuntu. At home I tried MINT and kept that and then found out it's Ubuntu based.

On target boards for systems we send out: we always give the manufacturer's default distribution a try, but have also used MonteVista, Debian, or just kernel.org and built it ourselves. We very rarely use anything like a "full" distribution for a product.

Exactly as long as a distro fits my needs. This is the reason why I use different distros for different purposes. On my desktop and laptop it now is Gentoo, but I still have Slackware, Salix and one Debian machine (actually a VPS) around.

I've been using Debian as my main OS more than 8 years now. Once in a while, either on spare hardware or a VM, I'll try something else.