With Castamatic's Automatic Gap-Zapper you can increase play speed of spoken parts without losing intellegibility by shortening silent parts.
You can enable Gap-Zapper opening the fx panel by tapping the Audio Fx icon in the bottom-right corner of the player.
You can choose three different levels of zapping. Usually the "Classic" setting is enough to obtain 10% increase in most podcasts. You can pick the "Hard" or "Extreme" settings to speed up even more the spoken parts.
Consider that "Extreme" setting can clip part of the initial and final parts of phrases in podcasts that are produced with a very low audio level.