It's not guaranteed, but it happens often enough to be regarded as pretty typical.
I think the most important thing to take away is that by AmEx's own estimation it is reasonable to request a 3x increase. And then they may give it to you, or counter-offer a lower amount, or say "wait a bit".
FWIW, when I previously had an AmEx revolver I was unaware of this custom. For my first CLI I asked for 2.5x and ended up getting 2x. As always in the credit world, your mileage may vary.
Just to give you an idea, I was at 7,500 and requested the full 3x CLI. Amex countered at 19.2k. So I got about a 2.5x CLI from them.
Jeez that's great. I can't wait until my 2 months roll around. I haven't even got my card yet and I'm already looking into the future. Do you have to spend a lot of money on the card per month or is it kind of like a unwritten thing and it doesn't really matter?
Some have had experience where it does not matter. Others who have gotten the card and requested 3x CLI and did not spend much have gotten rejected. I personally use Amex as my main card (originally my charge cards) but moved my spend on them over to the BCE to show activity. Typically I put about 1.5k per month through them. Now I use both charge and credit from them just to mix things up a bit.
Ok I will try to use it as much as possible to show activity. I used to have the Green card but I canceled it a few months back.