Yvie and that other bloke can only see one person at a time, so what must the rest do ?

Do they watch TV at night or practise their songs ?

they have dfferent things to do ,vocal training,dancing , record the charity track they be doing,film stuff for the website , shoot their vts for saturday etc etc rehearse

I should think both Yvie and Brian have various seconds-in-command to whom they can delegate the task of overseeing rehearsals with contestants while they themselves focus on each act. I can't imagine the contestants just sit around doing nothing until Y&B are ready for them.