… is there something that might make Podium think there is extra data for playback?
Podium may be rendering ’til the case when, a)there are no more timeline events, b)the ‘tail’ falls below a certain threshold. The ‘tail’ could be signal level remaining after a reverb or delay, for example. The threshold which Podium considers a signal level the user wishes not be discarded could be -infinite dB (silence). The faders on tracks go to -48dB, next stop silence, so that may be the level for gating the render. Some processes may take a long time for signal to decay to that level.
MLS’ advice ensures the render is trimmed to the desired time range.