How far can you safely push the 3L mercruiser?

[Warpa1]

I had asked this on another forum, but they are more into the much bigger boats and very much stuck up their aholes

From what i understand the cruising revs are 3k and wot is 4400-4800, now its my understanding wot throttle is a bad thing for even 5 mins? So can you travel at 3.5-4k without over stressing the engine? This is on a 1750 from 1997, well looked after and very well maintained. Only reason i asked is because i normally run at 2.5-3k and opened her up to 4k for a few mins coming home the other afternoon, and i must say it was a whole new experience The difference is speed seemed amazing and it also seemed to take the choppy sea a lot better as i just skipped the top of it instead of getting all the slamming.

Im just trying to understand that if 3k rpm is the cruising speed, why have neqarly 2k rpm left that could be used