I just read a fascinating and very logical article about contact centers and wait times published by Northwestern's Kellogg School of Management. If call centers or contact centers are core to your business, or if you've ever waited on hold to get help or support, it's a must-read.
With algorithms and analytics at the core of so many businesses today, the challenge of wait times and hold times to get problems solved is directly tied to customer satisfaction and over time, customer retention. In the cases where there's a competitive environment the customer's ability to leave is directly proportional to how much support is in place.
For example, Apple customers really don't have an option on where to go for support and help, as Apple is Apple. If you're an Android user and you get tired of the challenges of waiting on hold for Samsung you buy a phone from LG or One Plus and move on. If you're a Dell customer, you stick with Dell until you get tired of their support times and move to a Surface from Microsoft.
In Apple's case they can keep adding support people, but as a long time customer (since 1984) their support times have increased not decreased, only because they can't really keep up as they have gone from being a single line product company with only computers to now being smartphones, tablets, watches, TV boxes and more. Even Genius Bar appointments that were usually obtainable in a day require you to book in some cases farther out than to see your dentist.
If you're a monopoly market-based business, your customers have nowhere to go and wait. But if they can leave, they eventually will.
Read the article and think about your support process.