MP Setup - OC v Custom Module Differences? (Reloading.)

I was trying to understand how and why an OC NWN2 game allows a direct game reload compared to a custom built module that requires the player to select a PC to play - which, in turn, then offers another GUI asking whether to use the selected local vault PC or the version of the selected PC already in the saved game. (NB: They have to choose the current in-game version or else the module will break.)

In brief, with an OC game, when you select “load game”, the saved game loads with your current PC, skipping the “Select PC” screen that interjects with a custom module.

Now while I can understand the need to “select” or “create” a PC when first starting a module, I do not understand why the game would continue to offer a PC selection at time of reloading a saved game, which it only does this with a custom built module.

I was looking into this as a way to “improve” the way the game is reloaded when returning to the game. I also wondered if it had any other impact on the game performance wise.

NOTE: I have taken steps to ensure the player loads the correct PC, but as I recently noticed the OC does not require these steps, I wondered if anybody knew how this was managed?