Personally I only use quin or Tri for certain races, to cobble a runner [or 2] at odds I think has a good chance of winning together with the fav. just in case.
If I think the fav. is seriously flawed [Tomorrow: Haradasun, Miss Finland, Marching and Weekend Hussler who is coming back 400m] I'll take advantage of the good win odds on others.

It up to you Shaun. Nothing wrong with a staking plan [% of bank or pocket ect.], as long as your not reaching for that worn out old chestnut 'progressive' staking. It will increase your winnings AND your loses because you have no way in knowing if your next bet is going to be a winner or loser.

You could use a very mild progression for interest, but you will just [eventualy] mildly increase your winning ....and losses.

It would be great to only increase our bets when we know they will be a winner:-)