This is tricky. Most people either think too short term, or too long term.
However, as with everything, the better option is usually in the balance.
It all depends on the situation. If your company is dying, of course you have to think short-term to save it. Optimising your “About us” page for long-term brand commitment is just wrong.
And if it’s the time to think long-term, make sure it’s long just enough, not more.