One way is as good as the other, maybe, but DSOs are designed, primarily, around zooming in.
Says who? Nobody provided any evidence that zooming out is not the way an oscilloscope works. The fact it (recording beyond the screen) is possible on many oscilloscopes suggests that those are actually designed to work this way. It seems Keysight event went through the trouble to make single acquisition mode different compared to normal acquisition mode to support zooming out after a capture by recording beyond the screen. No, the problem is definitely that some seem to be stuck in the idea that you should always zoom in and use exact settings. Even if making those settings and zoom window adds zero benefit to solving the problem at hand.
You are now inventing that Keysight memory management was made the way it is "for the purpose of enabling zoom out" while presented with plenty of evidence that it doesn't even work that way when used in a scenario as explicitly designed by you.
You are confusing (at this point obviously intentionally, not wanting to admit the truth) that fact that something exists, is not a proof of intention. That kind of memory setting is probably there because it was easier for manufacturers to implement memory management, or for support for digitizer mode when using scope as digitizer. Or whatever. Only instrument designers know.
And zooming in and out provides same benefit as it provides same data for analysis. That was also proven several times by different people.
Once you capture data, both methods have same data and same analysis capabilities. I said that at the begining, tv84 said it very nicely (and more concise than I'm capable off.)
But, at this point you are insulting those that prefer to use proven techniques and use exact settings as being backwards.
They are stupid because they read manual. Nice.
Your only reason to insist on you way is that you refuse to learn how to use zoom mode. You simply hate it, for some reason.
So you devised method that you like better, that works on some scopes, and don't on others.
And you like it, and you find it useful. Good for you. I'm happy for you. And you shared it with us. Thank you for that. That was nice of you. Unfortunately, I couldn't find no merritts in it for me, for what I do, and how I do stuff. But thanks anyway. It was a gesture that counts.