It sounds impossible to me too. I'd like to meet the therapist who's able to be emotionally available to 8 - 10 clients in a day and who also has a life. I can't imagine who could do that and be emotionally available to each of their clients. Now, not to say there aren't "developed" therapists out there who could do that, but I think they are few and far between. I'm certainly not there.
I see 5 - 6 clients for 50 minutes each and I have a good 20-25 minutes in between clients. I need that so I don't carry stuff from my last client forward. I need to discharge the energy if any has built up. That way I'm hopefully present with each one.
I also think it's a question of boundaries...not taking on others' stuff. It's an energetic thing. When I'm not listening to my own body as I go along in a session I can easily be left with residual feelings that a client may not have been in touch with. So, for instance, I might be left with a tight jaw that's characteristic of unresolved fight. The client wasn't in touch with the anger he or she was holding and I felt it and carried it.
Body psychotherapy is enormously helpful in this regards. Because I frequently get my clients to "check in" they tap into their own emotions and it's less likely that I'm left holding them.
Spirituality has also been helpful to me. I recognize in an emobdied way, now more than ever, that I cannot interfere with another person's journey...I cannot "rescue" them from their own feeling. Working through their own feelings will help them in their next step. If I take on their feelings, there's a good chance they won't learn from this experience and it will affect whatever is coming up for them next. For instance, if a client comes in really angry about something outside our relationship and I respond by being all upset, I start to carry their emotion.
The hard part as both of you alluded to is being emotionally available when it comes to our relationship. That's hard, but so worthwile for the client. It's challenging for a therapist but also tremendously rewarding.