First off, regarding Dragon's Lair. It was the first game to successfully charge $0.50. So the coin box being the same size as a normal $0.25 game made it far more likely to overflow.
The rule of thumb that most operators talked about BITD was the 6 week rule. If a game couldn't pay for itself in 6 weeks, it was yanked. If a game paid for itself in a week (or looked like it would basd on the daily tally), they would drive over to their distributor and pick up as many as they could, usually at least 2 or 3 more for each location. Most places also had a bottom number (usually $200 - $300 a week) where any game making that number would get yanked and put in the warehouse to be replaced with the latest and greatest.
Location also had a great deal to do with the earnings expectations. There was an hierarchy to locations. Non-mall arcades across the street from high schools tended to be the most profitable. Followed by strip mall arcades. Then bar/bowling alleys/entertainment complexes. Lastly were the mall arcades. Oh, and the convenience stores (7/11, Tom Thumb, Quicky Mart, etc).
The mob involvement was quite real. They were interested in any business that deals with the movement a lot of cash, especially where it was difficult to trace. If your counts were getting too high, just unplug the coin counters for a while. Free unreported quarters. Need to launder some dirty money, clip a pulser on the coin counters for a while and infuse the business with a little "outside" makeup cash that gets used to buy a new machine that mysteriously doesn't show up. There are a lot of ways to cook the boks in a pure cash business.
ken