"an overlap of * weeks" を使った用例で、少しわかりやすいものを見つけた。
USA Today に関連するニュースサイトだ。文脈が必要なのであえて長めに引用する。

ここでは、まずは女子のバスケットチームを活動させた後に、男子のバスケットチームを
活動させたという話をしていて、女子から男子に移り変わる時に、あいだには
3週間の重なり部分（オーバーラップ、引継ぎ機関）を置いたのだと言っている。

We started with the girls in early August and went right on through, rolled over
to the boys and went through March. That whole month, because we were
so successful with the girls, we were playing as many games as you could play.
We'd have ★an overlap of three weeks★ where we were running two practices.
Beginning practices for the guys were just backing up and doing fundamentals
and getting ready for them.
https://www.newsleader.com/story/valleypreps/2014/12/30/waynesboro-91-state-title-oral-history/21063337/