As soon as you subscribe to any of the premium plans we start tracking the data for that account hourly. This means that your follower, unfollower and tweet count data should be no more than 1 hour old.
New follower/ unfollower data, however, is processed once per day.
For the free accounts, we do ask Twitter for the numbers throughout the day for all the accounts we monitor. Therefore, the stats for that day could be for any time during that day. Be aware of time zones. Our servers are in the EST (America/Chicago) time zone, so morning in Chicago could be evening in Australia (or somewhere else).
The frequency with which we track free accounts is usually once per day. For some low-activity accounts the frequency is lower.
Visitors and non-users
We track such accounts sporadically; highly active or larger accounts being tracked more frequently then low-activity or smaller ones.