What's right for one person may not be right for another. Many people do have jobs that require a periodic check-in and/or not being able to check in will generate more stress and worry than not checking in.
Today's corporate world is driven by email and other communications. Often people will return to an email inbox with a thousand emails. It's crazy but it's often the reality. Being out of the loop, for even a week, on some projects, deals, or inquiries can sometimes mean losing a client, a project going off the rails, or closing a deal.
When I was in the "corporate" world there were times I needed to stay in touch, especially if a client or project was at a critical point when my cruise or vacation came around. In those days Internet at sea was in its infancy but I did make a few cell calls in ports and I also received a few calls on the cabin phone. On the other hand I would evaluate a manager, director or group leader on how well his/her area would run when they weren't there. If it all went south then they weren't doing a good job of training and empowering their people. If it ran smoothly then they were doing a good job. I wish my bosses would have thought the same way.
On the "nice" side of it. Some folks like sharing their time in somewhat "real time" mode with friends and family.
It really boils down to what is going to make your vacation more enjoyable. You aren't going to change your lifestyle and personality in one week so why make that week less enjoyable by worrying about things. If twenty minutes or two hours on the Internet is going to make the rest of the time more fun then go online and take care of what you need to take care of. If you are spending two hours a day taking care of work issues then you shouldn't have gone on vacation.
Each person is different but, in the end, it's what you do to enjoy your vacation that makes it fun.