The biggest problem I see with this plan is that it's far too rigid. You can plan up to the 10 or 15 minute mark, but after that your approach should be based on your specific situation, not a preconceived build order. Smart enemies will be scouting you and looking to disrupt you. Don't be surprised if major fights break out before the 20 minute mark.
Now, against computers, the general rule of thumb is that if you survive for one hour, you've won. The computer is atrocious in the late game. Beyond the fact that it won't build superweapons, is terrible at building a powerhouse economy, and builds all the wrong units and capital ships, it just doesn't know how to command a battle. It will frequently send its attacking fleets directly into a death trap, and then when defending... well, suffice to say it does just about nothing right. The end result is that if the AI hasn't killed or crippled you by the one hour mark, it's never going to.
A four hour game is virtually unheard of. Maybe in a huge multistar free for all, but otherwise games are highly unlikely to run for more than 3 hours. Most games could be called (that is, it's fairly obvious who the winner will be) within the first hour. As a result, the majority of your strategic planning should be for within the first hour. That is where the most critical fighting will be.
Then I start invading enemies and using pirate bounties to keep larger fleets occupied.
This is actually a bad thing to do against human players. They won't send their entire fleet to deal with a pirate raid, they will leave one capital ship on defense duty to ward them off. The pirates won't kill anything (pirates are actually very weak units stats-wise) and will only serve to level up the defending capital ship. After the first raid, pirates simply aren't dangerous anymore and bounties are a waste of your money.
At this point I have the most powerful economy in the game. I'll continue to spread outwards slowly 2 planets at a time until I have 100000 crystal and metal and 500000 credits.
Everything at this point and beyond is moot. If you can afford to build up that much excess cash, you already have such a massive advantage over your enemy that you should have won A LONG time ago. A human player would have already surrendered to you on the grounds that you just have such a powerful economy... but more likely he will have attacked early and prevented you from ever getting it in the first place (hence the danger of planning too far into the future).
