Do you use "Save As" when you want to save your project with a unique name?
It's better to simply use File > Save.
"Save As," or better yet, "Save a Copy" is meant to be used to save project backups.
When to use Save
Use File > Save as soon as you open your project in order to name it. This is a crucial step, so do so as soon as possible after project creation.
Use File > Save as a general practice as you are editing. In general, every 10 or so minutes. That's been my practice for years.
Use File > Save after performing a series of editing functions you don't want to lose should something go wrong, like a crash or hang.
Try not to get into the habit of using "Save As" to simply save your project, or for any of the reasons above. It creates problems!
Doing so brings up the dialog box to remind you that a project with that name already exists.
Clicking through the warning, usually works, but has the possibility of corrupting your project.
Use File > Save instead to avoid this potential pitfall.
When to use "Save a Copy" or "Save As"
Editors use the "Save a Copy" or "Save As" commands mainly to create incremental versions (back up copies) of their projects. "Save a Copy" seems to make the most sense for today's workflows.
Save A Copy: saves the document under a new name, but the original stays open for editing, not the new one.
Save As: You save the document under a new name, and the new file stays open for editing.
The technique: Use "Save a Copy," for example, as follows: If you want to back up an existing project called, say, "Paris," but want to archive a copy of the file, then choose File > Save a Copy, then enter the name "Paris_01" at the top of the dialog box and then click Save to a folder called "Paris_Back Ups" or the like. You can then continue working in the "Paris" project, and so on. After a number of days, you have a nice set of backups saved up. Delete the older ones as you work through the project or simply archive them.
You can work with the "Save As" command in the very same fashion. The workflow difference is that once you create a "Save As" incremented copy, you are then working in that new project. The previous version can then be archived as the back up. Save As might make sense in an episodic series, like editing a daily vlog.
Right. Save a copy.
Some thoughts: "Why do this if we have an Auto Save system?" Well, to put it bluntly, pro editors are, historically, an overly careful lot when it comes to safeguarding their own work. They abide by rules of thumb, such as, "always have at least 3 copies of your recent project in 3 different locations, one being in the Cloud." So that is why editors make back ups and why you might consider doing the same.
Editors create back ups for a project in case the working version of the project becomes corrupt or damaged (this happens). It's a safety backup maneuver that takes project back up one step further, and with more control, than your Auto Save project folder. Most editors create these "Save a Copy" backups throughout the work day, say three times a day. It's totally optional, but I found that it has saved me hours, if not days, of lost work. The back up folder in function is essentially a back up of your Auto Save folder, which in spite of its controls, can fail to provide a crucially timed back up
In the interests of being the guardian of an expensive film project, as they say, it's better to be safe than sorry. Imagine if your project becomes corrupt. You reach into your Auto Save folder, all the copies are corrupt, as well. What to do? Calmly head to your Paris_Back Ups folder and retrieve one of your expressly created back ups.
As a photographer, after loading images from memory cards onto the computer, I then make copies of those images I plan to work on. From that point on, I "save as" everything.
Working on a photo just now, I accidentially hit "save a copy" and the thought occurred to me to find out the difference between the two and if one or the other is better at preserving the quality of the image.
As I understand it when you 'save as' the file you are them working on is the one you just saved. If you save a copy you are then still working on the origional, not the copy. The quality for both is the same.