The blockade rush is a tactic for tiny galaxies against one opponent. It works against intellegent AIs and makes for a fairly fast paced game with combat hapening early. It is somewhat cheap since the AI doesn't seem to realize it's being blockaded, or can't develop a counter. It has drawbacks in that you sacrifice some of your inital turns during the crucial landgrab phase building offensive ships instead of expanding. If you fail to contain your opponent in time, you will have a severe disadvantage to overcome. But usually within 30 turns you will be able to tell if you can catch up to and contain your opponent in time. So if you didn't get there in time you can always just restart without much time lost. This also works well in the first few campaign missions.