I still do the bed of hot coals method and just watch over it and monitor it closely. If I notice it’s getting a little hotter then I like I adjust the height and watch it toast slowly. 2-3 hours in good weather usually yields great results. The neat idea of the radiant heat set up with electric or gas fired radiant heat is that it can be controlled and set up in a shop if safety precautions are taken. Much of the guess work and repeatable heat treatment can be done from bow to bow. The obvious problem with the coal bed is getting consistent repeatable results from bow to bow. The last batch of bows I did this way were all heat treated same bed but some had deeper cook then others. Efforts are made to minimize this to some degree but invariably still get some variations in heat from spot to spot. To minimize some of these hot spots and get more consistency I’ll move bows around and shuffle them from spot to spot. It helps but the temp controlled electric heat treatment system set up would be ideal for consistency. Just my 2 cents.