Pareto

Because you'll spend a thousand hours or two in total to learn a new language, you can save yourself a sizable chunk.

Achieve that by applying The Pareto Principle.
It says that the effort that you put in doesn't always lead to a corresponding output.

Typically, 20% of the effort can give you 80% of the result.

(And 20% of that 20% can give you over 50% of the result.)

In non-mathematical language, you can get an A with a lot of effort.
You can get a B with a weekend's effort.
And you can get a passing C doing your work on the ride home in the bus!

So ask yourself: What is helping me the most?

Then do more of that!