The Clans won most of their battles during Revival, but how often did they lose mechs in their victories against IS forces? I know they took some losses from elaborate ambushes like walking into a swamp full of flammable gas and from environmental factors like falling into magma and an asteroid hitting a dropship. A couple mechs were destroyed by ASFs on Rasalhague. I'm wondering about the more typical battles which the Clans won. I'm just asking for your perspective, but if you have evidence from canon sources, so much the better.
I'd venture that, say, at a third of the contested worlds in the first three waves, they suffered at least 25% casualties destroyed; cored or pilot killed. If two-thirds of conventional planetary militias were blitzed w/ no significant Clan losses, but Clan clusters could not simply declare worlds strategically secured while IS forces could mass firepower in open battle, Solamna deployment and pacification might cost more 2nd Line units cored, plus accident and sabotage, than Clans may judge worth notice.
Clan clusters could not draw as quickly from salvage and Isorla, like the IS, for the fronts, because Zellbrigen and the risk of Chalcas if an 'illigit' BattleMech is the only replacement available. "Get that 2nd Line jalopy off of the Bloodnamed's lawn!"
On this account, the wear and tear of Revival's frenetic pace, more OmniMechs may go down to a lack of maintenance checks than enemy fire in a week-long Revival blitz, that yet won't merit notice or remark by high command.
The way the Clans keep score muddies the water. The symbolic victory is a unique factor in Zell. Dogged insistence on observing form before declaring a grand melee, may, laughably, guarantee one casualty for the Clans at the outset of every engagement. That sort of thing.
Don't ask for my math homework, though.