Learn English – “To be or to not be” Is it grammatically correct? , that is the question

Infinitives are typically more "abstract" than gerunds.

"Abstract" would mean things not derivable from direct experience or observation. Whether something is abstract or concrete in a given situation depends heavily on the speaker and listener and how they perceive something, so it's hard to provide definite rules. But here's a heuristic that can be used:

• When you speak of something philosophically, you are tending to be abstract. "To love is to be human".

• When you are comparing or giving advice, you are tending to be concrete (not abstract) because you would have had to experience or observe to know. "Walking is better than running."

So based on that walking would be preferred.

The marked infinitive, for example

to err

resolves to something like a noun; it plays a nominal role, so that it can be used as a subject or object:

To err is human.

The question-word why wants a verbal complement that resolves to an action:

Why use more than one fork, one for salad, one for the main meal, one for dessert?

Why go to the beach during a thunderstorm?

Why take the crowded highway when you can take a quiet back way with little traffic?

Why sing in the shower?