Do they do a hard pull on your credit report when you ask for a credit increase?
Amex I think depends on the person. I did asked to a increase of 33% of my line 6 months ago (because 33% given my history felt to be my limit since I've worked in this industry b4). I got it instantly online with 1.5 yrs clean payments and moderate use. However, my sister with 4 years clean history and a $500 line got hard-pulled last week. But she was asking for 2k so they wanted to make sure since that jump was so high. But she revolved. The gave her a mound of reasons to deny it, some to me were just petty and redundant. I would say that if you stay at 40% or less of an increase (ie 5k to 7k) then they probably won't do a pull unless you had a really low line to begin with and revolved.
post edit: sorry yeah 500k revolving, that would be somewhat off.