Re: Upper lower, or full body for 'unscheduled' training?
Well since most muscles recover around the 36 hour mark it'd make more sense to put 48 hours between training the same muscle groups, with the exception of calfs, abs etc would you could probably train most days, but I wouldn't train each muscle everyday myself, the science doesn't back it up really unless doing say heavy squats one day and body weight squats the next, which I'm sure isn't the case.
Upper/lower is a great choice.
You can just go
That's what I tend to do or
If you love something let it go,if it comes back to you it's yours,if it doesn't it never was.