description of automatic increase of Spot instance quotas

The "Amazon Elastic Compute Cloud User Guide for Linux Instances" contains in the chapter "Spot Instance quotas" in the last paragraph with the headline "Request a quota increase" the statement: "Even though Amazon EC2 automatically increases your Spot Instance quotas based on your usage, you can request a quota increase if necessary."

Even after thorough research I didn't find any explanation how EC2 increases Spot instance quotas automatically, especially for instances with those quota types whose default quotas are set to 0 on new accounts. Especially for these instances new users need an increase of the quotas and should be interested in a way of doing this automatically.

On the other hand I also looked for an explanation what criteria the AWS support uses for deciding quota increase requests. It should be in the interest for the users as well as for the AWS support that such requests meet the AWS criteria in advance to avoid long lasting questions and discussions. Especially interesting is the question if increase requests below a certain level will be approved quickly and without questions so that simple tests with only one instance can be done quickly.

Thanks.