Wiggy,
I can confirm. When Colin Barnes was DFO he insisted on it. It became 'over my dead body Barnes', that people would move seats in LH and have to go shorthaul first.
In my case(1988) I went from RHS 747 to LHS 737 and then back to LHS 747 all within 6 months as nobody else wanted to move. Friends who went onto the shorthaul Tristar for their first command (how does THAT work) were back on the 747 having spent so little time on the Tristar that they had been unable to give sectors away due to insufficient command time.
After that huge waste of money the system fell into disrepute and first commands were on any type.
As an aside, at that time the (new) 744 fleet was having a hard time recruiting experienced F/O's as they'd be frozen for 5 years and therefore miss out on commands due to the back to shorthaul nonsense. A small number (6?) negotiated a guaranteed (in writing) right to left command if they would go on the 744 - and that's what they did. The system fell apart about a year later.
S