I am wondering the same as well.
My understanding is that the 6 month CLIs are per customer, not account.
But I am not sure about the 61 day CLI for new accounts.
Can someone chime in pretty please 
Always been curious about this too.
LIMITS IN CARD DESCRIPTIONS
Its per user, Primary SSN.
I have a BCP and a Business Reolver. i asked for a BCP Increase at 61 days got it, asked for a increase on my Buisness revolver at its 61day mark and it got though the whole porcess and then said we can not grant the increase because one of your cards had recived a increase in the previous 6 months, or something to that effect.
Starting Score: 617Yes thats correct, 3x limit up to 25k. when i tried i i was at a 9k limit didnt go for 25 when for 20k and was approved. im wonding at the 6month mark should i add the 5k to my BCP or get my buisness revolver up.
@Credit_Ranger wrote:Well, that would appear to answer the question pretty definitively for all of us.
I guess the best thing would be to decide which card I woud rather have the CLI on.
The SPG was opened with a $9,500 credit line. My understanding, or at least what I have read here, is that one can request an increase of up to 3x at the 61 day mark and that one can count on a SP up to 25K.
Does that sound right? Id love to have a 25k credit line on one of my personal cards. Most are now in the 10K-15K range.
AMEX seems to like me. Probably because I run 30k/month through my PLUM card. Then they credit $450 toward my next statement, so I like them back.
...Ranger out...
If one card is higher, request the CLI on that one. You can get a larger total CLI, and then transfer some of that credit line to the other card. At least I think this would work. I've never transferred any credit line with Amex. I don't know if they have any restrictions like no transfers within a certain time period.
@OhioCPA wrote:My understanding was that by transfering some of your limit from one card to another you are "increasing the limit" on the one card and this will fall under the six month limitation on CLI.
Here is the wording from my online request to increase the limit on one of my cards. I jumped the gun by one week.
"Our bank policy does not permit us to increase the line of credit on your account within six months since increasing the line of credit on one of your existing American Express accounts."
Could still be useful. For example, if you had one card at $1000 and one at $9,000, you could increase the card at $9,000 to $25,000. In 6 months, you could transfer some of that, say $8000, to the $1000 card. Leaving you with one card at $17,000 and one card at $9,000.
You'd get more total increase like that than you would by requesting two increases on the $1000 card, which would leave you with both cards at $9,000. (i.e, $1000 to $3000, then $3000 to $9000, and the other card sitting at $9000).
This assumes of course that you'd get approved for the increase from $9000 to $25,000.