That's not Linde's interview. Okay, so you were wrong about the source.
This appears to be the report from the German group. It is in conflict with Linde's description of the two stations as "rescue" not "fire" stations. At best, we must say that we don't know whether Skylight 1 was used exclusively for fire drills. The German Group report says so, but a crew member says otherwise, and the German Group does not give its source for this information as far as I can tell.
ETA: Some more information....
The German group report that Vixen linked to claimed to be in agreement with JAIC on the use of drills, so I looked up
JAIC's comments. Here's what I found (excerpted):
As we can see, JAIC does refer to "Skylight No.
n" as referring to "fire groups" and "fire stations".
Now, this leaves open the question: are "fire groups" and "fire stations" limited to responding to literal fires on board, or are they for general emergencies? Linde's interview suggests the latter, but it's not altogether clear to me.
But this is the best evidence I could find for linking "Skylight No. 1" to a fire alarm. It is obviously contradicted by Linde's interview and some of the other citations we've seen, but it's from the JAIC report which is surely a reliable source.