You only get that huge SeeD exam bonus if you do it quickly though, I think - I did it and took ages, and ended up getting a rathre crap SeeD score
You must remember the time that is left when you get back to the beach is taken into account for your initial SeeD rank. 'Course, there are many other factors that may have played a role, like enemies killed, people you talked to, saving the dog, having good judgment at the Fire Cavern...lots of factors.

Random battles get harder at higher levels in FF8, due to monsters stats growing faster than you can keep up with junctioning to your own stats
There's one sure-fire way to keep that in order. 100 Death spells + ST-Atk-J = Most battles being reeeeally easy. Or just use Card on all of your enemies.

then i bought the 3 gunblade buy getting card mod...
Only the third one? 1 Chef Knife (from Tonberry card) + 2 Star Fragments (from 6 Iron Giant cards) + 1 Turtle Shell (from either 3 Adamantoise cards or 2 X-ATM092 cards) + 8 Screws (from 2 Geezard cards) + 1000 gil = Punishment.

...Ehh, sorry for not exactly being on topic, but I already knew about that little thing. IMO, I'd just use the SeeD tests to get my rank up to where I want it, and 50 AP isn't a whole lot.