I regard 'First Aid' as aid to an injured person to keep them alive until 'Secondary Aid' arrives. i.e. not paper cuts or sprains.

A well ironed largish handkerchief and training are all I feel I need.

1. We are never far from secondary aid. No wilderness or ocean use, that is a different requirement.

2. I naturally always carry a handkerchief anyway.

3. Can be deployed in fractions of a second.

4. It will double as an expedient particulate mask with, surprisingly, a good protective factor. (yes, I have tested them professionally)

5. Does not generate any liability of use. Easily counts as 'good samaritan' in UK case law.

6. In almost 70 years of life I have never needed anything else, which may be a fact of living in the UK or luck. I doubt if I shall be challenged with needing more in my lifetime.