Turn on Trim silences in Settings → Playback.
Open Settings: on a phone, tap the menu button (☰, top right) and choose Settings. On a computer, Settings is in the bar across the top. Under Playback, turn on Trim silences.
Castria then shortens long pauses so episodes finish sooner. It's off until you turn it on, and it works on downloaded episodes. Episodes you stream play normally.