Tipping is not requirement for receiving excellent service. However, it is very much appreciated as it is saying to the guide: Good Job and thanks for a great time.
I hear stories from all over about guides that post a tip requirement: not good!
When I hire a guide as a fill-in as a second boat or because I am ill that guide receives full pay. No guide goes out and works for just tips.
When I receive a tip, which is 99% of the time, I immediately buy my wife a candy bar. Most times tips are between 10 and 20%. My largest tip was an all-expense trip to Mexico by one of my regular, (4-5 times a month), customer.