On this branch, trains operate between Leytonstone* and Snaresbrook via Hainault. There are other services that terminate at Hainault and serve only half of the loop.
*Trains originate from Ealing Broadway or West Ruislip
Monday to Friday: Every 20 minutes
Saturdays: Every 20 minutes
Sundays and public holidays: Every 20 minutes (no service on Christmas Day)
More information on London Underground including timetables from stations
can be found here.