In my opinion, the title of the procedure is self explanatory: Unreliable Speed.
żDo you rely on your airspeed indications?
-YEP: continue normally
-NOPE: don't try to find out why, don't troubleshoot on your own, just do the manufacturer troubleshooting procedure to confirm/get some reliable speed indication, or fly with reference to tables or BUSS if there is none.
It suffices with not relying on the airspeed, even if you don't have a clue of what is going on. It may take some time to answer the question and come to the conclusion that you actually don't trust your instruments. A mixture of airmanship, experience, knowledge and system warnings will get you to that conclusion if something is not all right with the speed indications. With time there will be more system warnings available, for example some cautions to advise of a non reasonable angle of attack for a given speed and load factor, or something similar. Helpful stuff.
Every time there is an ADR fault, or flags, you should check the consistence of the remaining indications, specially with pitch, thrust and automation behavior just in case you have got one of those two wrong computers voting the good one out cases.
Most integrated ab-initio pilots do an MCC course after they get their frozen ATPL. It is intended to get familiar with airline type of operation, but it is also a good opportunity to practice hand flying in jets (sim, of course).
I did a lot of it, and I was able to fly an ILS without speed indication very easily. We flew pitch and thrust and we could perform the whole approach, from the hold till landing, just by using the pitch references we had for each configuration. When I practice Unreliable Speed in my company simulators, I just retrieve that from my hard disk and have a relaxed session.
I hate that they have removed the pitch references from the QRH on account of having the BUSS. Why do they do that? Is the BUSS immune to failure or what?