You have to be a bit careful, though. Consider a file named “README”. You make an edit to this file and then mimic that in “staging”. You go on about your business, editing other files. After a bit, you make another change to “README”.
Now you have made two changes to that file, but only one is in the staging area! Were you to create a snapshot now, your second change would be absent.
The lesson is this: Every new edit must be added to the staging area if it is to be part of the next snapshot.