Being a loyal FICO Forums member; I try to request CLI's each time they are "ripe" for one. In the current example (Chase), they will consider a CLI each six month interval. So, I wait until at least six statements have cut since the last request.
Here's how it's worked so far:
Account opened: 08/2008 CL 2,500
First CLI: 03/2009 CL 5,000
"Upgrade" to Sapphire card: 08/2009
Second CLI 10/2009 CL 10,000
I called and requested the CLI on Wednesday, 10/22 and got the 7 day message. Because of the information I've gleaned from this forum, I knew that I shouldn't wait for the 7 day letter but to call a couple of days after the request. I did, and this morning was APPROVED for a CLI from 5,000 to 10,000.
My APR has gone from an initial 14.9% to 13.6% also.
I charge between 0 and 300/mo. on this card and always PIF before statement.
Thank You FICO posters. Your advice and information is GOLDEN!!
Starting Score: TU 737 EQ 721
@score_building wrote:nice new 5 figure CL, WTG!!
how's that sapphire card...what did you PC from?
Thanks Score . . . 
The rewards are not-so-great since it's only 1 for 1 but there IS points for everything, like cellphone, car wash (paid monthly), etc.
I had the Chase Freedom card and when they offered the Sapphire, I just went for it.
The best benefit is the dedicated customer service. They are a cut above the average CSR and always friendly and helpful.
Edited to add: They did pull a hard from TU . . . . 