Use two possible outcomes to compare the offers
Suppose one booking costs $80 and cannot be changed. Another costs $100 and allows a change before a stated deadline. If the date stays fixed, flexibility costs $20. If the date must move, the cheaper booking may lose more than that difference. Read the provider’s actual conditions. A flexible fare might still require paying a price difference or changing before a particular time, so it is not automatically a free cancellation.
Test the terms against the uncertainty you actually face
Use a realistic example. If the visit depends on next week’s work rota, ask what happens if the shift changes on Thursday. Consider the difference in price, the last date to change, and whether everyone can accept the possible loss before booking.
Keep the decision date with the booking record
For a shift rota due on Thursday, a flexible booking whose change window closes Wednesday may offer little protection. Ask when the rota is expected and which time zone the provider uses for the deadline. If the uncertainty lasts longer than either booking allows, waiting or choosing another date might fit better. Once you choose, save the confirmed conditions, the total paid and the last useful time for making a change.