Good practice. This is what I teach my primary students. We fly out of
KLUK, a Class D airport under the KCVG Class B shelf. Really easy to
bust B, and with a FSDO at KLUK, well...bad things tend to happen then.
I teach my students that until they hear *specifically* "cleared into
Class B", they are to assume they are not, regardless of who they are
talking to, and regardless of what instructions they are given. I tell
my students to always say "understand cleared into Bravo, 49F". If
there is *any* doubt whatsoever, then ask the controller. Situational
awareness is paramount in any circumstance, but when flying around
congested, complex airspace, it becomes even more so. And this isn't
just pedantic, or because I don't want to see my students
benched...KCVG has MD88s and 737s flying around like mosquitos...and I
have a couple of accident reports printed out for my students to hit
home the importance of being careful.

Cheers,

Cap