If a Shedite inhabits someone for less than a full day without corrupting him, does it get dissonance?
On any 24 hour period where a Shedite has possessed a host, it has to corrupt someone. So if a Shedite spent a few months in Hell, it doesn’t get dissonance (no hosts, no need for corruption). It then pops up to Earth and inhabits someone for a few minutes. That’s when the clock starts ticking. (As a non-canon GM’s option, you can require them to corrupt every host they inhabit even for a moment. This works well for Shedim who are getting on the GMs nerves!
On any 24 hour period where a Shedite has possessed a host, it has to corrupt someone. So if a Shedite spent a few months in Hell, it doesn’t get dissonance (no hosts, no need for corruption). It then pops up to Earth and inhabits someone for a few minutes. That’s when the clock starts ticking. (As a non-canon GM’s option, you can require them to corrupt every host they inhabit even for a moment.