Ultramax Rival spindle set up

I'm looking for some help understanding when I would prefer the 10/10 spindle set up vs the 7/15. I have both sets of spindles and caster blocks. I've asked other Rival riders at the local track and nobody could really say other than it's driver preference. We've only rode the 10/10 set up. The handling is fairly decent but occasionally fight a tight condition on exit.
Thank you for the explanation. Are baseline camber and caster settings the same for both set ups?
Camber yes. Same initiative..... castor it depends. On lower bite right corner tracks I tend to run 10/13 castor with 7/15 Set up and 11/14 with 10/10 set up. At the Midwest Maxxdaddy I was on 7/15 set up and was down to 6/10 when I should’ve been on the 10/10 set up at 8/12 castor.
Castor is hard to judge. Like most say it is just preference but there is also speed gained or lost in the two different set ups.....