Apr-11-2017, 12:53 PM
2) Answer might be never - if you have 19+ versions of single file saved with a different suffixes, then its high time to start using version control system (nowadays its often git). With version system saving new version of a file is "cheap", so you can (and should) save your file after every "major" change. You wont have directory full of dozens versions of same file and with meaningful commit messages and possibility to compare changes its much easier to track your changes or revert to some previous version.