The point is that you have no way of knowing up front how long they will take. One series of calls I was not to speak with the same representative twice. To a big call center that is not a big problem. With a small call center it can mean a heck of a lot of calls in order to reach enough different associates. With the series of calls which I did this past week my average wait time in the queue was about 7 minutes. That series of calls was long distance without a toll free number and I did them on my cell phone which has anywhere minutes and I never use all my minutes anyway. But it meant that the average call was around 15 minutes and the write up of the shop took another 10 minutes or so, so it came out to about 2 calls per hour at $8 each.
Other calls have required me to dial a toll free number, put in my code, put in a client code, put in a project code, put in the phone number to be dialed and then the call would start to ring--after 35 digits had been entered. Mess up 1 digit out of 35 and you start again from scratch. Get a busy signal, you start from scratch. Get a terrible connection, you start from scratch.
Every kind of job has its own exasperations.