I use KO and usually play in shoe games.
Heads-up, I'll just play one hand. Faster and simpler. (It's pretty rare that I'm in a heads up game).
Conversely, it has been written that you can bet 2 hands @ .75x your usual max bet, and have the same variance as one big bet. Having two bets out might also make it easier to disguise your bet ramping. But I still lean towards one hand.
With any other players, my goal is to eat more than my fair share of cards in positive counts. Since 2 spots usually requires double bet in each, I'll do this as soon as the count even remotely supports making a 4x bet. Usually for me this is when the running count is 3 or 4 over the key count.
If playing single deck, the considerations are different, and while I don't understand them, I know it's preferable to have two spots in play rather than one, because more rounds are dealt out that way.