For the Venues type Sprwt checks the venue's availability for the chosen date and start/end time before saving. Possible messages:

• "This venue is already booked for the selected date and time. Please choose another venue." – another proposal or order already occupies that slot.
• "This venue is unavailable for the selected date. Please select a different venue." – the venue is blocked/closed on that date.
• "Please select a venue before continuing." – the Venues Location field is empty.

The page also shows a live capacity badge: if Number Of Guests exceeds the venue's capacity you'll see "Guest count exceeds venue capacity by N" as a warning.