TL;DR

I spent an afternoon estimating the upside of moving a ranking page. The examples pointed to around one extra click a month, a useful number to have before committing time to SEO work.

what did the ranking page estimate actually show?

I spent an afternoon estimating the upside of moving a ranking page. The examples pointed to around one extra click a month.

That estimate gave the SEO work a concrete scale before I sank more time into it.

when is an estimate enough to make the decision?

Sometimes the estimate is the whole decision. If the likely upside is around one extra click a month, that is useful context for deciding whether the work is worth doing.

The estimate did its job before implementation: it made the possible return visible.

FAQ
How do you estimate the upside of moving a ranking page?

In this case, I spent an afternoon estimating it from examples. Those examples pointed to around one extra click a month.

Is SEO work worth doing for one extra click a month?

The estimate gives you a useful number before you commit time. Sometimes that number is enough to make the decision.