Also, something I suspect that WitW does not, and probably cannot represent is the effect of cumulative damage.
The various oil targets, synthetic oil plants and refineries had to be run at close to full capacity 24/7 365 starting in 1939 ... there was no spare capacity (and additional capacity couldn't really be built unless the Germans built, for example, fewer AA guns ... which would have been ... counterproductive ... considering) ... so the ongoing allied bombing raids, while they never destroyed or shut down these plants completely, did cause cumulative damage that made them more and more vulnerable.
At the beginning, for example, a near miss within, say, 50 meters or so would spring welds etc. that would then have to be repaired ... a trivial delay in relative terms. But, as the years passed, and damage piled on damage, ever further away 'near misses' could cause the same sort of damage. Since allied bombing accuracy was never enough to actually hit the target directly with enough bombs to destroy it, this increasing vulnerability to ever more distant near misses made the reduction of capacity and temporary shutdowns or all or part of the plant's capacity ever more easy to achieve.
Yes, the 'big' or 'key' target strategy was a failure in a sense, but the cumulative damage and the forced diversion of resources from potentially more productive defensive or offensive production had a huge unseen impact that is only starting to be understood in the last 20-30 years.
Author, Space Opera (FGU); RBB #1 (FASA); Road to Armageddon; Farm, Forge and Steam; Orbis Mundi; Displaced (PGD)