I have a saddle pack thing that flits between the Pretty Bike and the Bloo bike. It has sufficient gubbins in it to get me home. CO2 wotsit, spare cartridges for same, spare tubes, spanner, fixer for tbe use of, nitrile gloves, three cable ties, tyre levers, multitool, bit of colgate tube to use as a tyre boot.
I had reason to delve in it today, where I discovered the CO2 wotsit in my case I did not have. Goodness knows how many rides I've done with it missing, fortunately without need to use it.
Durano plus FTW