The benefit of a Time Sert over a Heli-Coil is two-fold.
First, the TimeSert tooling spot faces the threaded hole so that the sealing surface remains square with the threads. This assures a more likely complete seal by clamping the washer evenly around its circumference.
Also, the TimeSert insert being one solid piece instead of a coiled "wire", it is not prone to being "picked out" of its threads at the leading end and is therefore much better suited to applications like drain plugs, where the bolt is repeatedly re-inserted.
Regarding torque wrenches and specs and such, unless the manual specifically states otherwise, torque specs are, as an industry standard, quoted for "clean, dry" threads. What was the last time you installed any drain plug "clean and dry"? Thought so. Lubing the threads can cause the same amount of torque on a bolt to increase the actual clamping force by 20% or more versus dry threads. Torque wrenches have their proper place, but experienced "feel" will serve you better with things like drain plugs in general.