Yes the spend credit is limited to one per day. I have checked my own Mariner points and we have always been credited with 1 point for spend each day we have had the Have it All package in place. Our only cruises where we did not get the full credit for spend pre-dated the Have it All option. We are nearing 5 star status as a result.
ONBOARD SPENDING BONUS:
One bonus credit will be granted for every $300 spent in onboard purchases.
This is calculated on the combined folio charges for all guests on the booking, regardless of who signs each charge and who pays the bill. There is a limit of one bonus day for each day sailed, and 3rd and 4th guests on the same booking do not earn the onboard spending bonus.