The email thread gets longer when the decision keeps finding new ways to remain indirect.

Threads grow because nobody has said the thing. Each message adds a qualification, a suggestion that someone else might weigh in, a question that postpones the choice by one more round, and the length is not evidence of thoroughness but of avoidance. Everyone is being polite, and the decision is quietly ageing.

When a thread passes about six messages, stop writing and name the decision that has to be made and who is making it. Offer two options and a date. Nearly always, the discomfort of being direct is smaller than the cost of another fortnight of correspondence.