Blockchain.info shows a graph of transactions excluding "long chains" of more than 10: https://blockchain.info/charts/n-transactions-excluding-chains-longer-than-10

This seems to indicate that ~68% of all transactions in bitcoin are part of long chains (which just means they changed hands more than 10 times in a day).

Tumbling is mentioned as one reason these chains are created, but I would like to explore this deeper. What other reasons might long chains be created?

Would gambling create long chains? (continuing to send to a service that pays out sporadically to you and others)

Are there other examples where two parties would legitimately want to transact between each other rapidly on blockchain?

How often does tumbling create long chains? I'm not familiar with which services are popular and how many rounds are recommended.

It would be interesting to understand what is causing the popularity of long chains in bitcoin right now. Thanks!