Skipping any of the three sessions is treated by the route as the protagonist refusing professional support. The Willpower and Labyrinth resolutions are gated behind the work the sessions do - players who skip report being unable to reach those routes even with otherwise qualifying stats.
The community consensus is that the three meetings are not optional side content. Each session feeds the protagonist's stat trajectory and which late-game choices read as available. Players who skip Meeting 3 in particular tend to land on the Anger or Caught routes regardless of intent.
How this is verified: Not directly readable from the in-game config fields. The chain itself is A-level; the consequences of skipping are community-sourced and should be treated as C-level guidance.