Just wondering because I didn't, and I'm not exactly great at games (I was down to low life on my last character a couple of times).
 
To be fair I really liked this game and I know it's an all ages game but the battle system could have been at least as challenging as the beginning of a pokemon game.

I died a couple times. Before I got my 3rd character there were a couple big guy fights that got some lucky blows in when I missed a block (I am a computer gamer and not used to the game pad).
 
Overall it was still really fun, well worth the money.

only when I purposely ran or made my self die because I had hit B and missed some story elements before a battle.

Nope! I thought it was pretty easy, but it wasn't any less fun because of it. 

I did a couple of times by trying to be too clever. 
 
"I shan't attack the guy with low health because he is poisoned and that will kill him" then he doesn't quite die, gets a hit in and then one wrong button press and I'm boned.

It was an easy game but I did die 3 times in total when I forgot to equip the right battle patches and costumes, but it only happened when I didn't take care of mages because if they buff someone they can take out your party in 1 hit practically. Once I learnt that I never died. Except the first time on the final boss because I was trying out some new costumes I had just earnt but they weren't very good.

I died on the last guy 2 times before I got my stamps in order.  One time he had 10hp left and the first time I missed the button press so he one shot all my guys haha.  Otherwise, I didn't die up until that point.  It was an easy game, but very fun.