To answer the actual question (about saving money) I'd like to see prescription waste tackled.
I'm on a few medications for an autoimmune condition and have had numerous experiences over the years with being unable to get my prescriptions updated correctly in a timely fashion resulting in surplus medication. For example in order to get one medication I had to accept 3 months worth of an incorrect dosage of the other medication because the consultant letter hadn't reached the online pharmacy who dispensed my medication.
I knew it was going to be an issue so I called pharmacy, they didnt have the consultant letter but I had it in my patient portal and offered to send it over which they refused. I also chased my team for the letter, made several calls over several days but in the end due to running low on one medication I had to just accept the prescription as it stood, knowing I was going to waste 3 months of medication as they wouldn't let me "just" order one and wait for the new script to arrive for the second medication.
There was also another time my hospital switched providers and I was sent a duplicate order. I had 10 weeks supply and they sent me another 3 months. As soon as I realised I was being sent a fulll script so early I called to try and postpone the order from the new pharmacy / supplier but again "computer said no" and I ended up with a huge backlog of medication and of course ended up having a dosage change before I made a dent in it.
I'm on quite a few support groups for my condition and this is a country wide issue thay happens in numerous trusts.
TLDR a good way to save money is to allow more autonomy with patients on long term medical conditions to manage their own supplies.
FWIW my hospital accept my surplus medication, which is a sealed and prefilled one use injection, as they use it for training new patients to inject and they even supply in emergencies (for example if someone comes into clinic and the consultant changes dose, the clinic have a supply and they can provide an interim amount of prefilled injection pens whilst the new script it being sorted).