About every 15-20 hours of running time you should grease the thrust bearing on the pump with Extreme Pressure red grease. If you don't keep grease in that bearing ugly things might happen. Change your oil both at the beginning of the season and at the end of the season, and after each 40 hours of running time. It is pretty simple really the thrust bearing keeps the pump shaft from trying to push your crank on your engine out of the front of the block and it takes a beating.
When it come's to greasing the front bearing I have a different look at things. A regular service of the front bearing at the begining of the season is all you should need until next spring. For those who would grease there front bearing after a couple trips I feel are over doing it. That would be like every couple trips in your car you pull the wheels and grease your wheel bearings. The only time I can see over greasing would be if the boat took on a lot of water and the front bearing was submerged then and only then would I over grease. One area that is overlooked is the tail shaft area. I do reccomend checking the oil in the bowl after 2 or 3 trips because with the small seal in the bowl they will leak oil out and require a refill.On the other pumps that require grease I service this a couple times a year depending on overall use. Remember the housing that holds the front bearing is only so big and over greasing will push past the seals and create a big mess.