Personally when I first started recreational use 6 years ago...
"100 hours" sounded like alot.
and then I became educated talking to mechanics and noticed...
"1000 hours was alot"
and after being a commercial user and speaking with daily livelihood users on a frequent basis...
"5000 hours" is alot
Law enforcement and tow operators easily put 3000 hours on a set in a year...sometimes they swap out every 1-3 years.
Difference is: They HAVE TO MAINTAIN THEM in order to extract that lifespan and its always built into their budget.
Can you do the same and extract the life out of yours?
I sincerely say that If I use it daily, I do not flush it. Occasionally, I use Salt Away to rid the cooling system of excess salt when I have forgotten to flush regularly....I know, I know cardinal sin. ..
But the 100 hours gets done and thats the simple 2 part key to keeping them running....flushing and service.
BOnus points if you use an additive to remove carbon:
Yamaha Ring Free
MErcury Quik Kleen
Thats the saving grace...removing carbon buildup from the motor.
This is hours of dock talk and wrench wisdom condensed into one post....