BOINC v7 waits upto 24 hours to report finished tasks, if where's no other reason to connect to project. Some of the reasons are:
1: Cached work drops below the minimum cache-size.
2: Where's more than 50 tasks to report.
3: Where's less than 24 hours until deadline.
4: Where's less than minimum cache-size until deadline.
5: Asked by project to connect every N hours, WCG atleast before used multiple days here so wouldn't normally be used.
6: To send trickle-up message (not used by WCG).
7: If user manually hits "update".

The biggest difference is #1, while with old BOINC-clients new work was asked for if cached dropped below minimum + additional, for v7 it's only asked if drops below minimum. If the additional is set to 0.5 days, it's a good chance won't need to ask for more work more than twice per day, while if additional is set to 1 day or more, chances are will only need to connect once per day.