I was a freelancer for twelve years--many of those years in Los Angeles. For eight years I hired and supervised freelancers, so I've been on both sides. One eventually comes to know freelancers' idiosyncrasies and plans accordingly. (For if they didn't have idiosyncrasies they probably wouldn't be freelancers.)
Clients are our friends. If we get mad at anything, get mad at the clock and calendar--not the client. Clients can also be unreasonable. (It's their nature.) They are usually dealing with unseen pressures we wouldn't even want to know about . . . But once the contract is signed The Client is one of the family. Success is when they come back for more.
One of those old guys with frizzy white hair said that, "A problem well-defined is a problem half solved." Then he died. But seriously folks, the best way to have a smooth operation is to have clear communication throughout the organization and the production process. Clearly defined goals, understood by all; clearly defined responsibilities, understood by all, eliminates the " . . . but didn't we talk about this?" confusion which is generally followed by a bad adrenaline rush, a sudden flush of blood to the cheeks and a couple of late nights catching up.
Working for yourself is a good way to sharpen these communication skills. I have. Plus, I just have a natural aversion to wasting time and money no matter whose budget it is.