The only “hot mopping” I ever used was COAL TAR ENAMEL for protection of surfaces like the in and out side of water mains 48″ dia and larger and out side of gas mains and some concrete storm tunnels.
Using hot coal tar enamal is fantastic for protecting surfaces from external corrosion BUT very seldom used indoors.
Some roofers use “hot mop” process
when applying 15# felt in layers before adding gravel to the roof surface.
Or use hot mop to hold down insulation prior to using BUR system
When installing my 4 PSF sheet lead I do not like using the hot process as this type of bitumen has a tendency of cracking over the year leaving possible voids.
For this reason I use “Cold” applied tar base like flashing cement or roof cement depending on the season.