I don't think I've worked on an IVR project when the business people didn't suggest using "tricks" to keep callers in the system. You know what I mean by tricks: disabling the zero key, or playing a routing menu when zero is pressed, or using a non-zero key for transfers, messages that falsely state long queue times, or putting the caller back in the system after they request a transfer. Often the tricks are used in IVRs that are pure misery to try to use. Businesses have a reason to try to increase automation rates - it saves them money. The best way to increase automation rates is to ensure that your automation is useful and usable to your customers. Unfortunately, getting your IVR to that point takes a lot of work, and keep-'em-in tricks are simple to implement. Some business folks take the easy path, and insist on tricks.
The tricks almost never work, or don't work the way the owners intend them to work. If a caller really wants to talk to a representative they'll figure out a way to do it. Eventually. And once they get to a real CSR after they've been plagued by IVR tricks they often aren't very happy. I listen to a lot of calls between customers and IVRs and then follow the calls into the call center. Some customers remain calm with the CSR after a poor experience in the IVR. Others do not, and take out their frustration on the CSR. No one goes away thinking better of a company after a miserable IVR experience.
My recommendation to companies considering using tricks to keep customers in the automation: work on the quality of your IVR first. Monitor, survey, read the reports, improve. Once you're satisfied that the IVR operates flawlessly you can consider using some small inducements (a nice way of saying a subtle trick) to keep callers in the IVR. If it's done properly you might be able to increase your automation rate slightly with no cost to the user experience. However, it all depends on first getting the IVR right. Do the hard stuff first, worry about the tricks later.