As of version 8.6, tickets no longer generate schedules or count towards capacity. The recommended approach is to assign users to a workspace. This would act as an operational project and you could allocate X% of a user's time towards that bucket, like Support
or Maintenance or something. The workspace schedules will then decrement from availability.
You can pick up the actual hours against the "operational" workspaces by associating the appropriate ticket types to the workspace. That ticket time then rolls up to the workspace.