Which you should use are often unknowable because it's often about how the code is driven by the data - you need to know the characteristics of the data to know

Which you should use are often unknowable because it's often about how the code is driven by the data - you need to know the characteristics of the data to know how the code will behave, only then can you meaningfully talk about picking a 'better' heuristic. Analogy: otherwise you're just optimising the design of a car. But optimising it for what? speed, efficiency, reliability, price, weight, carrying capacity... You first need to know how it's expected to be used. I guess local inlining might sometimes be an unconditional win, but even then only under specific circumstances. (disclaimer: I know something but am not an expert)