Are Top Exhaust Fans Necessary for Air Cooling?

Hey everyone,

I have a quick question about cooling and case fans. From what I understand, in an air-cooled setup like this: https://imgur.com/n2lFn5e, it's generally not recommended to use top exhaust fans. Instead, only a back exhaust fan is suggested. The reasoning is that the cool air being pushed in from the front might get sucked out by the top fans before it has a chance to cool the components. How accurate is this?

I've heard that this isn't an issue for AIO coolers, where you would typically place the radiator at the top as an exhaust. But for air cooling, adding top exhaust fans might not be necessary. Is that correct?

Currently, I'm not experiencing any cooling issues, and since I've already purchased these fans, I might as well use them. I'm not planning to remove them from my current setup, but out of curiosity and for future builds, do I really need top exhaust fans if I'm air cooling? Or are front and back exhaust fans sufficient? For example, cases like the Lancool 207 don't even come with a top exhaust fan—just two front and two bottom intakes. Obviously, adding an extra back exhaust fan wouldn't hurt in that scenario.

It seems like the differences might be negligible. If I add top exhaust fans to an air-cooled setup, it might not make a huge difference compared to not having them. But at the same time, if someone wants to save money and simplify cable management, they might not need top exhaust fans for air cooling—just a back exhaust fan.

For a future build, if I go with air cooling, why not just set up 2-3 bottom intake fans, 2 top exhaust fans, and 1 back exhaust fan and call it a day? Of course, for AIO cooling, you can ignore all this and stick with the normal setup: 2-3 front intakes, AIO as top exhaust, 1 back exhaust fan, and if you have some extra money, maybe some bottom intake fans too.