I imagine VJ that the FTOs have no personal limit on how many people they will take to their assessment day - after all they will get paid £200 - £210 per person so why would they limit the numbers....as long as you meet their initial criteria.
Which still makes me think you would be at a disadvantage if you pick the most popular FTO!
I first applied to BA 16 years ago (ish), got through to the final stage, and there was none of this pay to be assessed business then. I'm not sure it is sitting very well with me. Especially as they are giving out dates already - what's their real criteria? Bums on seats = lots of fees?
"Cattle market" is springing to mind, but maybe that's because I'm older, and grumpier.