Brian,

It is an assumption.

The assumption results from comparing the fit of Jett engines to most others.

I suppose it is to break the extremely tight TDC bind, because 1 whole minute is not needed to get the bottom end wet enough with oil; this takes only a second, or two at most.

Then why don't we ask Dub, or Bob27, his representative in RCU, about the purpose of the full 1 minute rich run?