That's my question too ... why would you consciously choose to fly 30°
off? why
*wouldn't* you line yourself up with the centerline (*straight*-in)?

To get there faster, although from 20 miles out you probably won't notice
any difference. Making a 30 degree turn on short final is simple - in fact
many controllers will say "proceed directly to threshold", or some similar
instruction while you are turning downwind to base to get you in faster if
there is traffic in sequence behind you .

Ya know, if as the subject says, cleared straight in Runway X, report Y miles
Final, it's reasonable to assume you were to report Y miles out on final, not
on a modifed base leg or something. It'd be different if the instruction was
"cleared straight in, report 5 miles.", IMHO. In the latter case, it means
coming inside the 5 mile bubble, in the former, I at least would take it to
mean "on final" not on base or an entry leg.

Yeah, it's splitting hairs. It might matter if approach had other inbound
traffic on that runway and had told them to be alert for someone 5 miles out on
a straight in. "Traffic not in sight" makes me feel very uncomfortable, if I
have to say it or I hear it from an airplane that's supposed to follow me in.

Now I'll go find some more hairs to split