We use a web scenario to check for the availability of a web site and tie the associated trigger with an IT service for SLA calculation.

The web site has a daily downtime scheduled in the regular Configuration > Maintenance section and that gets applied to the IT Service Times as downtime, as expected, and SLAs are calculated correctly.

Now every once in a while we have a one-time maintenance window which is outside the regular daily downtime. So that our SLAs are not affected, we have to create 2 maintenance periods, both in the regular place and within the IT service itself.

Why can't the IT service associated with a trigger use the proper trigger downtime period for problem time calculation?

It also doesn't help the fact that ad-hoc IT service downtime entries will keep adding up in the IT service downtime window because if they are removed, the SLA gets affected, even after the period has passed.