last year we had 7 on track most of the time with 8 in one or two sessions when asked. From my perspective last year, with 8 on Wakefield at a time you are cramping the cars up a bit. This would be OK if everyone was running at the same pace and was experienced with overtaking and being overtaken but for the sort of day Mr Wasabi is setting up 8 is on the edge IMO.
10 at a time IMO will exacerbate the speed differential between cars on the track, upsetting the flow for the quicker cars as they back off for those they catch and also for the slower cars as they worry about holding others up.
All that said, let's see how many we get and sort it out on the day. Last year the last 2 or 3 hours was pretty quiet with some drivers spent and some cars spent.

