Surprisingly, nobody has ever complained about the weekly email digest defaults. Literally nobody!
Note that we only send digests for a maximum of 1 year past your last visit date and the digest default is weekly. We could probably move that down to every two weeks as a default. We also filter digests to just trust level 1 or higher posts, and digests obviously are not sent if there are no new posts…
But the status quo seems to meet people’s expectations or at least be a reasonable balance between reminding people that your site exists, by mailing them some interesting content, versus nagging them constantly with spammy emails.
I am always interested in hearing specific suggestions to make the digests better.