No.
My idea is better. Have it as a solution focused conversation like they do for disabled student allowance. Give the person the money to enable the support that has been identified to help them.
The next assessment asks how the money was used to support the person and in certain cases looks to identify steps of improvements. The money might get more or less depending on how things have changed. If someone has made no progress at all (in certain conditions) then it might lead to questions about how they are spending the pip to meet the expenses related to managing their disability, and potentially a reduction.
Example - my DC was in their room not getting up and dressed, not washing, not eating anything unless I brought it in. We used our pip for PA support twice a week and now DC goes bike riding, which has rekindled their interest in plants and animals, and they have been able to help our neighbour look after their cat when they went away. There are still lots of issues with personal hygiene, use of washing machine etc.
Next pip review we can show the efficacy of that money in helping DC, and show that there is lots still to go, but with the PA support the future is looking better and we may even move towards voluntary work or part time paid employment. This would mean the money continues or increases to support the PA's wages. In other words, they don't take money away automatically if you admit there has been progress.
If you have spent money but there's been no change - eg the PA hadn't helped at all - then you would try to work out what needs to be different (eg meds review, different support worker, different focus of support).
If we hadn't spent any money on the disability supports except to buy a new bed (because the other was worn out from DC being in it 24/7) and just say "no change" at review, the assessor could reduce the money as it's not being helpful if literally nothing has changed in their mental health condition.
Obviously this system wouldn't work for some conditions but I think it might for some of the more mental health ones.