I am quite awed at how Mr. Harb's ski instruction has lasted through the years. Yo soy un Harbista. His triumph was to be first to marry clear written explanation to stop action photography. All kudos he receives should be shared with the photographer. Great attention should be paid to the "Hi-C" phase of the turn. Roll onward to Ron LeMaster.
As for physical training regimens, I strongly recommend core work ... the abdomen area - crunch, extension, and twist. The latter two are often overlooked. An objective in steep, uneven and bumped terrain is to have the physical capacity to ski it as if it were groomed.
Your striving to keep skis close together runs counter to an issue I have always had ... keeping my skis far enough apart. So, I'd suggest ignoring any suggestion you may have heard one way or another. To discover if you are perhaps leaning in to the hill (a no-no) or not using your inside edge adequately (a good thing) I suggest two early season activities.
If you get up to the mountain on a weekday early season, you will find it cold, icy, flat, boring, and deserted. A little thread of manmade snow sandwiched between a huge dismal pile of rocks. This is exactly what you want. Start with a magic carpet, perhaps. Work your way up to a beginner/intermediate lift. Your mission is to ski this terrain well on one ski. When one leg gets tired, use the other leg. You are forced to make turns using your inside edge and outside edge. You are forced to rely upon pressuring the ski's tip and relying upon the ski's sidecut to carve but you must also, with each turn, spill a bit of speed by skidding (What John mentions ... but go easy on his Wedln [proper spelling] suggestion ... a bit of that can take you right over the edge and you will be back in the 1950's.)What you will find is that it is far easier to make turns in one direction than another (outside edge is more difficult). Keep training this way ... dedicate a half hour or an hour to this one drill. Get good at it and you will never have another problem in your skiing life.
Another drill I learned in an adaptive clinic. Remember those edgy wedgies that the instructors use with certain students with disabilities? Don't ski with them ... you will break them. What you need is the adult model ... two heavier duty carpenters clamps and some 550 cord. Allow 10-12 inches of slack in the 550 cord. Ski at speed with the setup and give me some feedback. It's a totally eerie experience that will change your skiing forever ... hopefully for the better.