You can test twice a week. No need to be concerned after testing everyday for the whole week.
This will help you understand how nitrates add up in your tank and help you develop a regular maintenance schedule as V mentioned .IMO
50% a week should be good for most tanks not stocked too much so you should be fine with that now.It basically removes half the crap that has been produced through the week. % of water changed is % the nutrient is removed. I like to do at least a monthly 're set' and change 75-90%.I match temp and water parameters perfectly for this.
You should remember to mention you have Bolivian rams as they are not as sensitive or in need of the high temp as GBR. They do just fine at 76 or so..