It wasn't that "soldiers won't last longer" - it was that the division wouldn't last longer. Soviet doctrine solved the problem of maintaining fast advance wit

It wasn't that "soldiers won't last longer" - it was that the division wouldn't last longer. Soviet doctrine solved the problem of maintaining fast advance with fragile men and equipment by subjecting individual units to intense, but very short, engagements. Specifically, a field army would have "echelons", where divisions of the first echelon would fight an extremely intense battle to achieve a breakthrough. Once that breakthrough was achieved (or failed), entire divisions would be rotated out, allowing fresh second-echelon divisions to take up the battle. This meant that if your tank could only do a combat-week's worth of driving before needing to go back to a depot for refit, that was fine; your armored division would send its tanks to the maintenance depot all at once while the troops were recovering from their week in hell. For more on how this would work in practice, see this NATO write-up of Soviet doctrine (specifically starting at around page 2-5 in their weird page-numbering scheme): https://fas.org/irp/doddir/army/fm100-2-1.pdf https://fas.org/irp/doddir/army/fm100-2-1.pdf