No, don't adjust the default frequency before you send - just make sure the default is something other than "none" (otherwise nobody will get it), and then run the daily, weekly and monthly cron tasks.
If you change the default frequency each time, then everyone will get the digest emails 3 times.
If your preference is set to none, then you won't get the email - that's exactly what the setting is designed to do.
If you want to test the email for yourself, use the test facility in the Admin CP Tools menu instead.
You might want to install my Monolog
addon so you can see exactly who is getting sent what.