If you read the experts, most folks check their emails too many times during the day. Today, while giving a presentation on Intro to Networks and Networking Protocols, I talked about the fact that we had instant messaging (IM) available and that email should not be seen as the same sort of medium as IM. Yes, this was a rabbit trail, but while I was on it, I took an informal poll. What I found is that everyone checked their email at least hourly, most several times an hour, and some quicker than that. The problem is that we've turned email into IM, and as a result we've trained ourselves to use it accordingly. This is disruptive and counter-productive.
I know that since I've trained myself to check my email far less, I am far more productive. I still don't check it just two or three times a day, but what I typically do is I check it between major tasks. If I see something that needs immediate attention, especially it fits the 2 minutes or less window, I take care of it. Otherwise, I mark it unread and leave it until I have a larger block of time to process it. And I typically set aside a few times a day (about 3) to do the larger processing, which seems to have worked well.
On a related note, this is something I'm having to train my oldest son on with respect to Facebook. It's really, really easy to get hooked on constantly refreshing status updates. But like checking email constantly, it's definitely a productivity killer. I've scaled back on Facebook where I check it a few times a day and that's usually sufficient. Anything more means I'm actually wasting time, and if I'm wasting time that means I'm not putting it towards something I consider more productive and important. That's basically what the frequent checking of either Facebook or email comes down to. Maybe 2-3x a day is not sufficient for the job you're doing. But unless you've made it an intentional practice to check email less (and train those around you that you will be checking it less), you still probably check it too often.