[Timshel]

Some strategic ones at least appear to have ben effective: https://en.m.wikipedia.org/wiki/Oil_campaign_of_World_War_II

Not do much for area bombing (cf https://en.m.wikipedia.org/wiki/Strategic_bombing_during_Wor...).

In both case we are talking of multiple years of bombing.

[heavenlyblue]

So not all of them were effective, and the second link specifically mentions bombings of Dresden and Hamburg as controversial.

And it’s very easy to be effective at bombing oil installations as they are not a part of the city.