The good software companies do these projects in the 3-6 month length instead of 1-2 weeks.
They absolutely plan where they want to be in 3-6 months -- they're generally quarterly OKR's -- but the only way they consistently achieve their targets is with weekly or biweekly readjustments.
The higher you go, the less agile it gets, because that's a horrible way to develop software, or any high-skill professional service or product.