Find some photos of CB&Q, Rock and MILW locos in storage, several parallel tracks worth, usually several locos on each track. Now, find the steam lines...
First off, define, "Rapidly." Unless you want to cause unnecessary problems, locomotives which have been in extended storage are fired up SLOWLY - twelve hours would be considered a proper start. Anything less can cause stress due to uneven heating, which can lead to anything from leaky flues and broken staybolts to cracked boiler plates.
In what way would it be cheaper to connect house steam, rather than pay one man to fire up several locomotives. You'd still have the man - the firing, boiler filling, oiling around, etc. wouldn't do themselves just because house steam was available.
I will admit that my own experience was with marine boilers, not locomotives. Water tube boilers are somewhat more forgiving than the fire tube boilers in locomotives, but we still had a, "One degree F per minute," rule for changing boiler temperature.
I repeat - locomotives were frequently stored where house steam wasn't available, and were fired from cold right where they stood. And nobody was, "Dorking around." The people doing the job knew what they were doing, how to do it, and why.
Now I REALLY wish that Mark was still here!