On the whole it seems a very good idea to restrict posts per day however one possible side-effect of that could be to encourage some posters to create multiple accounts (including industrial scale account farming).
Now that you mention it, I understand the need for a competent manager to clamp down on burst posting but in the past I have had some situations where I was busy away from the internet in general and had quite a lot of posts to make in order to meet my quota with just a couple of days remaining. It can happen to any participant but it does show aptitude from managers if they know when/who to sanction participants and when to give the benefit of the doubt (as well as know who the regular offenders are).
Who would want to be a campaign manager these days?

for me it was about discouraging burst posting (I had cases where people just made 20 posts on the last 2 days of the week). It has had the desired effect, I recently upped it to 7 from 5.
If someone makes 20 posts in a day, no matter who they are, they are clearly only thinking of their wallet and not anything else. If you are given a pass, then everyone will expect 1, which is how corruption starts.
This forum is accessible via mobile or desktop which means a person can login at anytime and make a post or 2. If you are away from the forum for 5 days and have 2 days left to get your posts in, the best thing you can do is take the rest of the posting period off. 1 person is no better than another, just more reputable in cases. I'm ok with someone posting sorta fast if it's on topic, decent quality, and not everytime they login, but 20 in a day is a no no matter who it is.