Such a great little puzzle. My top score is 199-- after a certain point it becomes impossible with all the 6+ cards appearing, you can't clear out your 1s and 2s anymore.
It's a bit like solitaire in that sometimes you'll just get an unwinnable spread of cards late-game, but sometimes they all work out. After another two weeks of playing sporadically I have just now got my all time high of 227. My strategy is to try and hold back playing a basket of 1 for as long as possible, as the 1s get more valuable the longer the game goes on. (Though funnily enough, in this last match I got *too many* 1s)