Outside of Educational establishments, iPad and iPhone are principally intended to be a single-user device - and are not intended to shared in the same manner as you may be accustomed when using a Windows PC or Mac computer - which has multiple user profiles/accounts.
For iPad and iPhone, signing-out of iCloud does not clear all locally stored data - and unless you are very careful when signing-out, you stand a very real risk of having your personal and/or sensitive data (such as your Calendar, Contacts and Keychain (Passwords) being merged with the AppleID/iCloud data next used to sign-in.
So as to avoid issues, you would be well advised to each have your own iPad - with which to solely use with your own AppleID/iCloud account.
To completely sanitise an iPad or iPhone of all data, it is necessary to fully reset the iPad - which for most is too great a burden for simple user-switching.
Settings > General > Transfer or Reset iPad > Erase All Content & Settings
Also see >>> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support