I have this question too. We see a rate limit of 100 for account stats calls, for 15 minutes not for 1 minute. This is very constraining.
I also have a similar question about rate limits, for other endpoints.
For example, getting the list of campaigns in one account has a URL similar to this:
https://ads-api.twitter.com/1/accounts/:account_id/campaigns?with_deleted=true
According to my reading of the docs, this is an “Account Read” call and should have a rate limit of 100 per 1 minute window, for Standard access. However, when I look at the response headers, it looks like it has a rate limit of 2000 per 15 minutes. 2000 per 15 minutes is actually more than 100 per 1 minute, but if you hit the limit you get locked out for a lot longer.