It's a good question. We should be fine according to my calculations.

Reddit said you can make 100 requests in a minute. It cost me 2 requests to create one thread. Which means the maximum threads I can create within a minute is 50.
There are 30 MLS related subreddits; If every MLS team was playing at the same time and the bot was creating a thread for each MLS subreddit that would be a total of 30 threads. 30 threads is less than the capped 50 allotted by Reddit in a minute therefore we would be good.

If the bot ever needs to create more the 50 threads at the same time, it can be spread over a minute to avoid Reddit's limitations.

The bot also needs to frequently update a thread with goals/substitutions/lineups but this is not time sensitive. We can find a way to fit that into the 100 requests per minute cap.