I've been running a double decoction schedule as so:
mash-in to reach 148F, hold for 60
--at 30-40 minutes in, pull decoction and apply heat to boil until first 60 is up
return decoction until reaching 158F or just under (I don't sweat up to 4 degrees shy)
start a 30 minute timer at the 158F rest
--at about 10 minutes in, or sometimes right away, pull a second decoction (also using whatever was left, if any, from 1st decoction), bring to boil till 30 minute second rest is done
return to reach 168 for mash-out. If any left, let cool and return.
This has been producing some fantastic flavor, and my efficiency hit 88% in a cooler mash-tun, which is ridiculous.
My only trouble so far is getting it to sit at 158 in the decoction pot for a rest of 10 minutes before going up to boiling. I'm using a glass cooktop installed in a work counter in my garage, and it seems to stay hot under the decoction, increasing the heat when I get to 158 and turn it off. I haven't gotten good enough yet to anticipate the extra rise. BUT - I'm almost done with my single tier. WIth that I will have my old turkey frier as a decoction vessel, so I can kill the flame completely for the 10 minute rest at 158, which will make things easier. Also the larger batch size and larger decoction should make it easier.
My new rig will eventually end up with a coil in the HLT to recirculate to control mash temps, so when that happens I won't worry as much about the decoction return coming up shy of the target. Right now that is often the case, but I can't really pull larger decoctions with the glass cooktop setup yet. Ahhh how this hobby pulls you in deeper and deeper!