Correct. Your activity level won't go down unless your posts are deleted.
I am not too sure what you mean by "exceeded the cap for the interval being calculated" though.
If he means posting more then needed to go up a activity level then yes its ok. You can post more then needed and you will move up once its time for activity level to be calculated.
You will not make it if your post count is under, or post count is under because of deleted post. If you are getting a lot of delete posts I would look at quality. Getting a lot of deleted posts is not a good thing, and could lead to a temp ban if you spam a lot.
By cap I meant that you cannot get more than 14 activity per week based on the time factor, unless I read that wrong. If the system checks every hour I was surmising that your activity would be incremented based on time first, but then it would cross-check with number of posts made and adjust the number if your post count somehow went down.
Thanks for all the answers appreciate it, I've not been spamming or running up post count on purpose anywhere so that's good, just posted in a few threads where we got the thread trashed because it was against forum rules.
It is 14 post per every 2 week period. If you post 14 posts you should go up one level. If you don't reach that number of posts you will not. And the weeks are based on your registration date.
All you have to do is post ATLEAST once per 2 week timeframe.