A question to the Sound Engineers out there

Depends on the studio, the end product, the people working on it, and the customer.

Don't confuse the recording studio with the mixing station, which may be just one of several review systems used.  Pretty much all digital processes now, mixing and mastering could be in the next room, the next city, or the other side of the world.

Sound "Engineers", back in the 70's- early 90's. In what I would call the "Golden age" of sound recording, "all" used the exact same monitors.
And I do really mean "All" engineers in any studio producing anything you would hear on the radio at the time. They were "Near-field" monitors that I cannot remember the model name of. But they were a 2-way, made by "Fostex". Small and looking like a bookshelf speaker, but for that time very expensive. Always flat-black with a pure white woofer, (5" woofer I think). I paid $400 for my pair in 1980. Hee hee, and I only paid $800 for the "sportscar" I was driving back then, just so you understand. Tons of clones that look like the old Fostex are around now. NONE sound like the Fostex's though. There was a very clinical resolution heard through them, a "Truth". That when used for mixing down allowed you to present a very even "field" of sound throughout the spectrum. They hid nothing. Horrible as a stereo, "speaker' though!

Tannoys were used in many famous studios from what I've read. 

In addition to the high quality studio monitors, many mixing studios in the analogue to early digital era also used Auratone speakers for near field mixing. Small box-shaped speakers that were perfect for how the mix would sound on the radio, typical home stereos, boom boxes.
Producers and clients wanted to hear the recording on the large monitors, but the engineer would always check the mix on the Auratones.

raysmtb1

Your reply reminded me of the movie That Thing You Do!, where they recorded the released track in a church.