I use a spreadsheet for timekeeping - there’s always something I don’t like about the time management apps. I keep different notebooks too - plus ambiguous file names for clients -so anyone snooping a look is not going to find out anything.
One of my clients keeps separate bags containing all of the information (notebooks, files etc), for each brand she works with, going to shows with her is a nightmare - none of these bags are small - she looks like a concierge!