I've only ever been to one fertility clinic so I don't know how most clinics do things or even the best way to do things: I just know how my clinic does things. And here it is:
To get a beta, you go in with the regular monitoring patients in the morning. Since it's just a blood test, it's easy in/easy out--no pesky dildocams to worry about. In the afternoon, a physician's assistant or nurse calls with the test results, unless your betas have plateaued and they think you have an ectopic pregnancy--then the doctor calls you himself (and you panic as soon as you hear his voice).
Now in my personal opinion, they call with results uncannily early in the day, but after you've been waiting 2 weeks (or, say 2.5 years), the time between when you give your blood and they call with the results seems endless. The earliest call I've gotten was at 11:30 am (negative), another was at 12:45 (chemical pregnancy), another was at 2:15 (positive), another was at 2:30 (doubling positive), and still another was at 3:00 (ectopic). So, the conclusion I draw from this is you want a call by 2:30 at the latest. Nothing good can happen after 2:30.
Oh, and here's the other thing: you can leave a specific phone number for the clinic to call with your results. If you work during the day, you can have them call your office. If you're out and about, you can have them call your cell phone. If you're deeply neurotic and don't really want to talk to anyone about your results until you've had a chance to process them, thanks very much, you have them leave a message on your home phone which you can pick up at your leisure--if by leisure you mean calling to check your messages every 5 minutes or so beginning at 11:30. If something unexpected(ly bad) is going on, the clinic somehow manages to find you wherever you are--at the office, on the cell, hiding under your bed.
If you're on your 8th beta day, anxiously waiting to hear that your numbers are continuing to fall, you might be exceptionally jumpy. You give your blood at the appointed hour and then start checking in with your answering machine at around 11. When there's no call by 1:00, you go out to lunch with some friends and turn your cell phone off. When you get back to work at 2:00, you check your machine, your office voice mail, and your cell phone, and finding no messages, you start to bite your nails.
You stop calling your home machine worried that the clinic can't get through because you're tying up the line. You busy yourself with tasks to try to distract yourelf from the passing minutes. You talk to your colleague about the intricacies of his gluten-free diet. You talk to another colleague about the relative merits of the AP Stylebook over The Chicago Manual of Style. You avoid noticing that it's 2:30, 2:45, 3:00.
You wonder what's the worst that could possibly happen: did your level not drop enough? Did it stay the same? Did it go up? You and your Infoholic Witch research what those options might mean. You worry that they'll want to give you more methotrexate and that you're going to have to tell your doctor that you started drinking again the moment your liver function test came back normal.
When the phone at your desk rings at 3:10, make yourself answer it. Sigh audibly when you hear a physician's assistant's voice instead of your doctor's. Think that it can't be that bad if your doctor's not calling himself. When she tells you the level is 130, ask what that means, why it isn't falling as quickly as it was before. Don't believe her when she says that it's okay as long as it's falling. Hang up the phone.
Instant message your husband, "When is this going to be over?" Realize you're crying and aren't sure exactly why. Splash some water on your face. Wish you were more like Jo. Update your blog.