I only use a monitor when setting up for interviews. I certainly am not going to drag a monitor around with me for b-roll, outdoors, etc. -- just to check color everytime I white balance. It's not unusual for me to white balance a dozen or more times during a day and I'm rarely connected to a monitor. If that makes me lazy, I'd say that makes you insecure about your method of white balancing.
White balancing through a flimsy piece of gel is not as easy or as fool proof as using the warm cards. I've done it both ways thousands of times, and beleive me, warm cards are easier, faster, and more conisistent. When I DO use a monitor, it's to check the composistion, lighting, contrast, etc. for the client, it ain't just to check color. I know what the color it going to look like without a monitor.