My mid 2013 MacBook air sees more use than any of my other devices.
I bought it for £100 a few years back and haven’t looked back.
Depends - average would probably be about 2-3 hours? Not great but not awful for my use.
I could replace the battery and improve this - ifixit sell the kits - but currently I have no need.
Ahh right, I’m getting about 4ish hours on my quite healthy battery on Mint, which felt short. I just fiddled about with TLP and dropped the discharge rate by half-ish. Otherwise it’s a great little low-cost device!