Celestial USCG exam: Which Questions use Observed Longitude / whole LHA?

I am dragging myself through a Celestial Nav self-study course for my USCG 500-ton Ocean Masters exam, and wondering how to know which questions requiring Pub 229 use Observed Longitude and a whole degree LHA, and which questions require interpolating your true LHA.

For example, a Computed Altitude & Azimuth of the Sun question requires a whole number LHA to get the coast guard’s answer, but a Gyro Error by Azimuth of the Sun question requires using your exact LHA.

How do I know which LHA to use when?


It has been a while since I have taught CNav or used 229, but I think all Azimuth problems will require Interpolation, but Observed bodies, (Sun, Moon, Stars) generally do not, unless you have to solve a Circle of Equal Altitude.
Good luck on your License.