For anyone using a more modern version of GNOME, here's what I have done.
I am using vanilla GNOME 3 on Ubuntu 18.04 (that is installing the base version of GNOME not the Ubuntu modified version). I think vanilla GNOME is the same as what RHEL uses too - at least that's what Fedora uses, so the following should work across those systems.
GNOME has two concepts for tabbing - tabbing between applications (the default) and tabbing between windows. Tabbing between applications groups the windows for that application together. I prefer (or at least I am more used to) tabbing between windows (and combined with Alt+Shift+Tab to go backwards).
In GNOME 3 at least this can now be fixed by just configuring the keyboard shortcuts.
- Go to the regular Settings > Devices > Keyboard > Navigation section.
- Disable both 'Switch applications' and 'Switch windows'
- Now neither Alt+Tab nor Super+Tab should work. Possibly do a log out/restart in between (I can't remember)
- Re-enable 'Switch windows' to be Alt+Tab.
I found that if both 'Switch applications' and 'Switch windows' were enabled then somehow Alt+Tab would still end up switching applications. This at least should be a solid method for guaranteeing that the Alt+Tab works as expected. You can then experiment setting 'Switch applications to Super+Tab.
This is what my keyboard shortcut settings looks like, note the 'Switch applications' at the top and 'Switch windows' at the bottom: