Yeah, I guess it's really a drag to be distracted by those pesky clients who are paying for the session.
When people are together in a room, they talk. So I allow a max of 1 person at a time in the studio and that's the producer. If the band doesn't like it when they hear it, I'm fine with touching up the job later. I don't call the job done till the artists have listened to their music on several systems anyway. It's so easy for little clicks & such which are incredibly common on computer-based recordings to slip through the cracks because of even the tiniest noise.