1st, no need to max it, even 80 effective is good protection vs snipers / crossbows. 2nd, because its chance to work does not depend on user's Will nor user's skill, but instead on attacker's resolve. 3rd, because tin cans are low mobility, meaning it's sometimes difficult or impossible to get into proper cover vs out-of-line-of-sight attackers, which is, again, often sniper rifles and crossbows for their long range.
Its resolve relative to your TC skill you ape
