Dependency on timescale in POODR Chapter 7?

[Paul Hamann]

Greetings. Forgive me if this has been brought up, or if I'm being dense;  I didn't find anything with Google.

For the schedulable role in Chapter 7, it's required to implement lead_days.  Let's say that the company providing the bicycle Trips discovers a lucrative market doing hourly rentals, or partial day trips. Is this knowledge of days inherently a likely future source of pain?  Would it be more painful and speculative trying to avoid it now?  What would a possible solution look like if you really were on this project, and hourly trips came up? It seems to share some of the same challenges as wheels and gears that can be metric or inches.  I could just convert everything to seconds, but that just feels yucky.

Thanks! Paul