Source: Automattic/sensei#4564 by @amroland

At the moment, you can drip lessons to learners only one by one.

Multiple lesson dripping at once:
I suggest allowing more than one lesson to be dripped for a given student at a time.
Or you can even allow all the lessons for a given student at once.

Bulk dripping:
Also, I suggest that you can allow multiple students to access multiple lessons at once by overwriting the dripping schedule.