Starting at 15.52, for each new trip just copy-paste an empty set of folders from here into the next available ID.

For example:

15.52 Milan conference, July 2025
      10 Planning
      20 Travel documents & visas
      30 Transport
      40 Accommodation
      50 Itineraries & schedules
      60 Expenses to claim
15.53 San Diego conference, August 2026
      10 Planning
      20 Travel documents & visas
      30 Transport
      40 Accommodation
      50 Itineraries & schedules
      60 Expenses to claim