I had plenty of material for a 20x24ft 2+ car garage.
I did spend the prior day grinding off the old paint finish, back to concrete. Rent a diamond cup type grinding machine, for 4 hrs (any other kind will take an entire day)
after grinding, use the acid wash - I used a mop, which helped brush down any loose dust also
the process of mixing the bags of epoxy is easy, wait 45 mins, then pour into a roller tray, and use 3/8 NAP 9" ROLLER
then repeat for the second bag of epoxy.
the paining took less than 1hr, inc painting 3" around all the edges first, then rollering 4x6ft section, then sprinkling the flakes
in all, excellent product.
the time is the preparation of the surface