So that would depend on what the other number is. Suppose you’re playing Wolf Run Eclipse and you’re chasing a mini-minor combo that adds up to around 40. Let’s say the mini is at 18 and the minor is at 22. You hit the minor, and the mini is still at 18. You would leave.
But suppose you start playing that same 18 mini, 22 minor. You’re spinning for a while (often the case on long-run games like this), and you eventually hit the minor again. However, you’ve been spinning so long that the mini is now at 31. You’d then play for the mini because it’s in solo-chase territory.
Now, I should caveat this with a suggestion to do what feels comfortable on games where combos are sometimes a consideration. That would include volatile and essentially uncapped (no must-hit point) games such as Azure Dragon, Buffalo Diamond, Magic Treasures Gold, Raise the Sails, and plenty more. Leaving a 31 mini on Wolf Run Eclipse, for instance, is not the worst move in the world.
But to answer your original question, it depends what that solo number is after hitting one end of a combo play.