I don't know if tight is the right word. They are just very methodical about the way they play, which is something they're hoping their readers pick up on and try to emulate. They definitely do consider who they're playing against, too, they always distinguish the spots where they're up against good thinking regs from the spots they're playing against randoms or fish, etc. So if it seems like they're playing tight, it's always for a good reason.
This series is the best MTT series out there imo, just for the way it shows you the right things to think about at the table.