Brent, It's not as much about knowing as it is figuring and being able to figure.
My trick I use is is simply counting out 20 yards at a time. When there's a hump or some elevation change in the direct line, the difficulty in figuring is increased . Even when knowing the exact yardage, these elevation changes or humps still require the knowledge of forethought to over come their simple deception.
I feel strongly that golfer's today have lost all connection with being sportsmen. It's not just golf either. I live in an area where outdoor sports are predominate. I discuss with many of the fisherman and hunters about their attitudes. To a man, they want their challenge eased. I see that desire as the root cause of the loss of the true sportsmen's credo. A credo that was prevalent when most of the classic courses we cherish were designed and built. It also explains why many of the ill-conceived changes have been made to these venerable courses over the course of the last 50-80 years.
Please don't think any one of us begrudges you your way of looking at, or, doing things. I sense we are just trying to entice you into trying it differently once in a while, and seeing if your level of satisfaction changes. That's all. And if someday your batteries fail or you forgot to download the course you are playing next, you won't be lost out there. You'll just be more challenged.
One painless way to approach learning how to do it, is to try to figure the yardage first, using your senses, and then turn to your device or caddie. Eventually, I guarantee you will be within a few yards of exact. And when you're not, there's something to analyze why you were off. Was it you, or was it the architect and/or terrain.