It's not too much I had a period in summer where they were visiting daily plus I was phoning them if necessary. I found this far preferable to being in hospital. I think generally if you are co- operating and utilising the help on offer then they're able to continue
When DH was really poorly he was visited daily for a number of weeks (at least 4 weeks but could have been longer that time is a bit of a blurr) and had a 24 hour phone number. Don't worry about it being too much, they wouldn't be doing it if they didn't think that was what you needed.
Admission to hospital is if they don't think that they can keep you or others safe by supporting you in the community regardless of hearing voices or not. Hearing voices on its own isn't a danger to anyone, although it can be very unpleasant and frightening.
I think the problem is that mental health Trusts are totally short of money and so there is an acute and chronic shortage of beds. Our local Trust has closed a whole dementia ward and cut beds on acute wards by 50% so they are using CPNs or other members of CMHTs to visit daily for patients who really need to be in hospital. They have a term for it here "Wards without Walls" - you couldn't make it up!!
Incidentally OP it isn't only "hearing voices" that prompts an admission. It's true that if someone is suffering a psychotic illness (with hearing voices being a symptom) and is not taking the meds, they may need to be sectioned under the Mental Health Act. The nature of this illness is that people are deluded so are convinced they are not ill and it's the people around them who are deluded! In such a state they need to be protected for themselves and others. A person can be sectioned if they are a danger to themself or others, and this can be the case for any mental illness.
Crisis teams in my experience are not much help - in our MH Trust they will simply tell someone to go to A & E as there is a MH liaison post in A & E. which I suppose is better than nothing. Mind a person would almost certainly have to wait for an age for the the MH liaison person. Of course staff are in a very difficult position knowing that there are no beds available for people who are in desperate need. They will try other hospitals in the trust or further afield, but it's just not right that patients have to travel 30 or more miles away from their home, which can be the case.
Upondown do you mind my asking about your mental illness - am assuming it is depression as suicidal thoughts are very common with this illness. Do you mean you are having these thoughts (known as suicide ideation) but don't really think you will act upon them, or is it more serious, and you have made plans. It sounds like it could be the latter as the CMHT are in close contact. Please take all the help you can get. Hope you have someone close at hand who understands the torment of mental illness and can support you.