What type of tournament are you referring too? Are these freerolls
? Turbos? Starting Stack? Rebuys? etc. Also what is your current opening range? Are you just blinding down or losing pots from early on? I take it since you are laying a lot of STT's you are comfortable in shove fold spots on shorter stacks?
All these have an impact, I would suggest widening your opening range a little and using selected aggression. I'd also recommend looking into pot odds
and using these to your advantage, you will find a lot of limped pots or open raise, call call call spots where there are many hands you can play in late position here that flop well multiway that perhaps you are missing out on, and you can really build a stack in these spots as fish are rarely folding in these spots. Are you attacking the blinds and antes oten once they kick in from late position?
Regarding the A5, Im personally open raising A5 from the small blind as standard , very rarely I am open folding here. Your ahead of the BB range here a large percentage of the time and even some of those your behind are folding in the spot depending on the player.
Hope this helped some and if you give more information perhaps I can be of more assistance.