Each project that wants an WBS has to put a scheduling calendar in first. If you forget, you get an error message.

Once you are creating tasks in the WBS however the system converts your estimated hours into working day using hard coded 8 hours. (I am all for 8 hour work days, that is not it) But suppose your calendar is different. Should the system not follow the scheduling calendar day length? That is why we have a scheduling calendar.

I can have a scheduling calendar with zero hours per day, or with 24 hours per day, it does not make any difference. So I suggest as an improvement one of two things:
- remove the requirement to have a scheduling calendar on your project

OR

- follow the day length in the calendar when converting hours into working days.