I've not had a MB where you had to spam any key. Just hold it on boot and wait until you see the menu. Select the one you want to boot now with either mouse or keyboard. This doesn't usually change the default boot order.
If you managed to install linux then this really shouldn't be a thing to get hung up on.
If the idea is they go cold turkey full Linux, good luck with that.
if the idea is they use their UEFI firmware boot menu, you're forgetting how unintuitive that is for most users with most uefi interfaces (spam hotkey at boot, wait for slow loading uefi, navigate to subscreen with boot order, find right menu item, either reorder and save or press F-key combo to "boot once now")