Deeday - never mind -'definitions' - what JD, IO, me and others are saying, having spent many bum-numbing hours flogging to and fro in a jet, is there is always an overall
loss of GS on outandbacks UNLESS the wind shifts, for which one spends hours praying........................Absolute still air (if only!) would be the only case to disprove this You never get back what you lose. (There's always the cost index, of course....shh!)
For the OP - just stick to DD's whizzwheel brief and worry not about all these esoterics.
