It’s a one size fits all process which isn’t really fit for purpose
Actually it is entirely fit for purpose. Of course managers know who is swinging the lead and who isn't. And once upon a time managers would sack people with impunity because it was their opinion that people were taking the proverbial. Then Employment Tribunals got involved and a number of employers were taken to the cleaners, quite rightly, because they could not prove that the employees were taking the proverbial. Hence proper sickness monitoring was introduced based on evidence.
I am old enough to recall, in public service, some employees saying that they needed to go off sick because they "hadn't taken their allowance this year" - when people get full pay for being off sick with absolutely no consequences then some, a minority, will exploit that. Some people took 6+ months of sick every 12 - 18 months. They had doctors notes and everything. Many of them suffered from "bad backs". That's why having a bad back became such a joke - an unproveable condition that the GP cannot dispute.
So the policy is entirely fit for purpose - it sets targets, it provides support to those who need it, and it ultimately terminates those who take too much time off sick. Oddly, the purpose of working is to work, and not be off sick; and there is a reason why sickness rates are highest where people get paid sick periods (and I think everyone should have at least some fully paid periods of sickness - so I am not arguing that paid sickness absence is a bad thing).
Incidentally, actioning stage 3 (termination) before contractual sick pay is exhausted is a breach of contract and has been held to be unfair in law, so whilst employers in the public sector, who routinely offer up to six months full and six months half pay can complete that stage, they cannot action the termination until sick pay is exhausted. That is up to 12 months paid sick leave. Which is pretty "fit for purpose".
If the OP wants to flounce off because, as a senior clinical members of staff, they don't understand that there needs to be sickness absence procedures then that is worrying - they seem to be operating on the assumption that they will need to have lots more periods of sickness rather than this being a bad run and unusual. As a fellow arthritis sufferer (disabled in law, highest rate of PIP in both categories) it is always a possibility, but I have no expectation that I will sprain my ankle or have a bout of sickness. But my last period of sickness, which was after surgery, was 10 weeks in 2018; I did end up in the sickness management process, and it resulted in huge levels of support for my return to work and staying in work. But yes, it was made clear, quite rightly, that a return to work and sustained attendance would be an expectation. I saw no problem with that because that is what I wanted too.