Hi Brist,
Largest I've done so far is 5 x 4 metres and it was OK although I was playing catch up for a while. Actually, for some reason I found it easier than my own kitchen ceiling which is 6 x 3. Total area is less but maybe it was the length I didn't get on with on my kitchen ceiling. My own ceiling was a near disaster with bits going off all over the place before I could get back to them. I really had to fight with that one!
Got a 7 x 4.5 booked in for a coupe of weeks time and I'm absolutely dreading it. To make matters worse it's got a light stipple finish. I'd considered splitting it into to sections and doing in two hits, one straight after the other to avoid an ugly join line. However, I've more or less convinced myself that I can do it in one hit providing I don't mind busting my gut trying to keep on tp of it.
Regards
Fred