I have one card from when I started rebuilding a few years ago. That's Merrick. It hasn't grown much since 2012. Lately I've been on a mission to see if I could get it to grow a little so I've been using it more. No big charges but a few things here and there. Maybe it's a coincidence or the usage was the incentive for them to give me an increase. I signed in a few minutes ago and saw that it went from $1600 - $2K. It's always going to be a low limit card but it doesn't have an AF so I don't have a reason to cancel it. $2000 looks much better than $1600 so I'm good with it.
This is the short increase history for this card -
8/20/12 - $1000. - 7/2013 - $1200. (Auto) 10/28/13 - $1600. (Auto) 5/30/16 - $2000 (Auto)