Facemount is horribly, eye-wateringly expensive. For the best results from very glossy paper onto very smooth substrates (no orange peel), it's pretty much the only option (unless you can get the Zenith equivalent)
With something like mediatac, unfortunately for a 24x20' print, you're looking at 24x17" of waste (plus the lead and tail lengths (another 41x12"), unless you are ganging up the prep of the substrates. So, if your workflow is prep the odd mount board here and there, then you'll want to go for a double sided mount film, with twin release. If you are looking to prep up multiple boards in batches, particularly if you are starting from larger sheets, then cutting down to size when needed, then a selfwound material would suit.
In the good old days, we were able to buy directly form the manufacturer, who would convert 41" rolls into 24+17" rolls, so we could carry all three sizes for maximum efficiency. Unfortunately that is no longer an option (nor I suspect would it be on your side of the pond)