I use the OT for more than 2 years now and never changed the CF Card.
I regulary save “All Parts” , “save Project” and “sync to card”
I heard of many OT users who lost their work.
Did I forget something or can I change the card now ?
Backup the card to a computer or clone the card if possible
…no.
only if you got two cards with the same content and a computer backup of that content…
and if you save to new from time to time, so you can step back to older versions of your projects either…this is’nt doubling up all audio involved, only the project parameters…
If you use “Save project” do you need to save each individual bank as well?
I do both as a precaution 
Backup, backup and backup.
Do the above, be organised, espcially if the scenario of losing your work, or getting corrupted projects will annoy you.