CM, no, the point is that a sqn with one crew working up to LCR, a senior crew winding down, and the other crews with graduated proficiency from New to old is not at 100%. The sqn may be declared but by definition has to be less capable than one at steady state, all crews trained and worked up. A case on point were the composite sqns formed pre-GW 1.
Desirable as that may be that 100% sqn is offset by the training sqn in work up.
In contrast the sqn with continually rotation of crews, slightly less capable, is more efficient as a greater proportion are always operational.