then sticking with the coding guidelines of the whole project is more important for maintainability

This can also be a sticky point. When they make sense sure, but sticking to them no matter what can cause more problems. Far too often I have seen some people try to stick with they style/way something was written before because they want to respect the code that was there before or don't understand why it was done that way. Only to squeeze their solution into it in an awkward way and bend over backwards to get it working right. But if they were to ask the original developer why it was done that way the answer is often just could not think of a better way at the time or I cannot remember any more or seemed like a good idea at the time, but it has not aged well.

Large projects are often layers of changes layered on other changes in additive ways that eventually lead to some very weird and convoluted structures. In those situations I do actually find undoing the layers of abstraction and just inlining all the function calls lets you make some massive simplifications and lets you better see new more robust abstractions you can then apply - things that would never be obvious from the original overly abstract code.

It is worth asking other devs though. Occasionally there is a legitimate reason for some jank in the code that cannot be gotten rid of some external reasons (ideally if you find these you should add a comment to explain this though).