I save the snapshot for that particular brew session and try not to alter the original. I’ll then adjust efficiency and whatever changes to the snapshot.
The next batch I brew will be the first recipe I built. IN my haste, I probably should have worked through the calculator a bit more, but if it turns out as I expect, I would consider keeping the recipe and revising it, brewing it again.
If I change things like the hops or grains from an original recipe, I use the Snapshot feature. It is a little tricky though on how that works. You have to be in your recipe, then choose to Brew It and click make a snapshot. The software creates a brew session which I delete because I need to go back and make changes to the Snapshot Recipe. After I make changes to the Snapshot Recipe, I choose to Brew It and it creates a new brew session based on the Snapshot Recipe. (One thing to note in doing this, every time you choose to Brew It, it will give you the option to deduct ingredients from your inventory. If you deduct ingredients the first time you select Brew It, and then delete the Brew Session, it will not add the ingredients back into your inventory, so remember to only deduct ingredients once or your inventory will be off.)
The Brew Session tab is where all my actual readings go. I do not go back in to the recipe after I start to brew and make corrections or updates unless I win an award or something, then I will just update the Notes section. It also looks like the Brew Session readings do not update the recipe. I can see this on the most recent brew I made, https://www.brewersfriend.com/homebrew/recipe/view/1648284/lichtenhainer. The snapshot recipe does not reflect my actual readings from the brew session. It already has a final gravity reading, and I am still in the brewing process. I see no place to go in and actual update readings such as these on the actual recipe.