For a novel problem (sub)domain that is great, if no prior optimization occurred globally dominant bottlenecks / inefficiencies still exist.

But once the worst bottleneck is widened to the same width as the second-worst bottleneck, you are from then on optimizing both until you reach the width of the third-worst bottleneck, and from then on you need to elevate all 3 to improve the situation, and so on.

to make it more concrete with an example:

you can identify that the friction on a bicycle comes predominantly from the front wheel, so you optimize the front wheel bearing/lubrication/... until you discover the front wheel has the same friction as the rear wheel bearings, so if you want to improve you'd have to improve both front and rear wheel friction, which helps until they have improved beyond the friction on the pedal bearings, from then on you need to improve all 3, until you discover the chain links became the friction bottleneck, etc...