No most if not all realy on the overwriting of the oldest files when the card are full, this is the quintessential dashcam feature.
Besides you dont want to save everything when you drive, just the little special / funny / shameful things you see ( and can protect from overwriting by pressing the manual event button )
And then of course any outright crash, which you will hopefully never have, and so in that regard the dashcam will be a poor investment.
64Gb is what i recommend for a dashcam / 128 Gb if its a dual channel system. You can of course go higher if you want to, but 64Gb should be fine for a cross state drive unless you live in a really large state or take the longest route.
64Gb should give you 8 hours of drive time before the card are full and start to delete the oldest files to make room for new ones,,,,,,, and thats okay too if nothing happened worth saving just as you set off on your drive.
Its a good idea to use the manual event button to save events, i myself have relied on mental notes for years, and really thats not optimal with a memory like mine.
This just mean you have to pay attention on how much space your locked files take up on the memory card,,,,, some cameras assign part of the memory card and can overwrite event files when that storage space fill up, in which case you do not want to use event button too much and forget to take files off the memory card, or have any form of parking guard running that can quick fill up the assigned space for protected files.
My B1W have 30% of the memory card assigned for event and parking guard event files, on this camera it work fine as the sensor are not overly sensitive so there are not many false recordings made that could be problematic in any way they are handled.
Yet other dashcams have no assigned space or overwrite of event files, so those can slowly fill up with event files leaving little room left for your regular recordings, and so if 60Gb of your 64Gb card are taken up with un- deletable event files you have 4 Gb for regular driving, and so dont have to get far from starting point before the card are full and so overwrite the oldest of your "normal" files.
I look at my memory card fairly often and normally delete the files in the "RO" / Read Only folder when there are about 20 of them, so about once every month i delete protected files, this is also a little buffer for me in case i forget something.
Also taking files off the memory card on the computer, be sure to copy them to computer and not move, moving files can cause problems with file structure on memory card and confuse camera.
Copy file off mean the file are still on the memory card, and if you do want to wipe card ( which are a good thing to do now and then ) then its best done with a in camera format of the memory card.