16 D10, the new way to go on 36.
Speaking of weird checkouts, I don't understand why Cross kept going for 10 D4 when on 18. I mean, I know know D4 is next to his favoured D18 but in my mind if you decide to split 18 then 2 D8 is a better way to go. Reason being if you miss inside on D8 then you'll end up on D4 anyway, it's not like you are going to end up on a double that isn't a multiple of 2. And it avoids a scenario where you hit 4 and then have to go for D2 down the bottom of the board. Finally, just in general I'd rather be on D8 than D4 as it reduces the chances of whittling it down to madhouse D1 if you keep missing inside. D8 is also a very common double to be aiming at so a world champion surely must be comfortable there.
I'm sounding a bit like Wayne Mardle here on the theory side and there's an argument that says different players favour different areas of the board so should play to their strengths, but even so I'll take a lot of convincing given that he's chosen to go with a double he'd probably end up on anyway if he missed D8.