24/18 13/10 is the normal opening play for 6-3, a bit better than 24/15. What has changed here, after our 5-1 opener?
- Our backcheckers are split, this means the number of indirect shots at outfield blots will often be about doubled
- We have an extra builder on our eightpoint, making a potential attack/blitz at split backcheckers more powerful
- We rolled 6 pips, with factotum's 9 pips this makes the race effectively near equal, instead of being a little ahead after a 6-3 opening roll
The first two factors favour 24/15, the last argues slightly against it.
After 24/18 13/10, we don't just have nines to hit that outfield blot of factotum (6-3, 5-4, 3-3 for 5 shots total), but also eights (6-2, 5-3, 4-4, 2-2) for 6 extra shots, totalling 11 hit numbers. That is a very significant difference.
Sixes and ones may be used to hit factotum off our barpoint, and especially after hits with ones, the extra checker we have on that eightpoint may come in handy in a subsequent attacking/blitzing game.
These factors are enough to make 24/18 13/10 the inferior play here, and go for the safer 24/15, leaving just threes to hit.