Take everything you hear with a grain of salt. Not to be a cynic, but I don't believe what anyone says until I have given some analytic thought to their words.
Keep in mind: There are only 24 hours in the day, and 7 days per week, etc.
Bigger is not always better or more profitable. You have to find the sweet spot to everything, and that takes work and experience.
Guys that claim they are running those kind of numbers are usually full of bunk, those that really do tend to be humble and keep their mouth shut for fear of giving the keys to the kingdom away.
Plan your work and work your plan, that way you can avoid the sew saw of randomness. Plan for a full schedule but prepare to run at 50%. Once you master that, plan for 200% and see if you can keep up at 100% of your facility output, you will find out that you cannot since there are always glitches, be it parts, staffing, or personal problems.
But the make it a main point, always try to have fun, even though some customers out there are very abusive.
As for numbers, here are some, 1 master tech, 1 R& I tech, 1 lube/tire, 1 manager and 1 service writer, 1 bookkeeper/secretary and 1 owner, revenues of $1.2 Mil, 6 bays, 3500'sq. ft. running at 96% with 6 days operating 56 hours a week.