How is manually setting memory depth and time base every time you want to change what you're looking at less keypresses than simply set timebase, press zoom, set 2nd timebase and position.
Memory settings are usually not on buttons or main menu so you at least need to press Acquistion - Record length -select length. That is 3 steps for memory set alone. Then you need to setup timebase for screen (making sure to keep sample rate in sweet spot that will guarantee your wanted full sample), and then you need to find a place in a buffer with delay command or knob, for which you don't have any visual aid, but need to find the right place blindly, pretty much zooming out to see where you are, moving displayed portion with delay, and then zooming in and keep repeating it in until you are at the right spot.
You see, after this thing kept going for a while, I went and took out my Micsig (which has both auto, and manual memory management. auto is default).
And I tried what you're saying and it was not less keypresses, but significantly more twiddling on average. You need to constantly twiddle back and forth with time base and position to look around. I set time base for full capture, press zoom, set secondary time base, set zoom position, and then after capture, i just move zoom position with finger on the visual map of capture. That's it. Yes it uses screen space for zoom. But it is way faster, more intuitive, WISIWIG, you literally see what you're doing. And, I didn't mention this before, you can disable zoom and move around with timebase and delays same way as you do... So you capture initial capture with zoom with all the benefits that has, and once you have your data, disable the zoom and move around as you would your way.