Some dates are wrong
1962 - Minnesota slalom skiers used Northland slalom skis. Warren Witherall, who had his signature on the ski cut 1.25 inches of the back of our skis and moved the fin forward. As a high-school student, I felt felt pain when he extended the fin slot forward with a big hand saw.
1967 - Just before the Texas Nationals I was trying to make a Maharajah ski work. KLP could make the ski work, but other skiers would just fall over into their good-side turn when they were on their difficult rope lengths. To widen the ski along front foot, I used a band saw to cut a slot down the right side of the ski from the tip to the back of the front binding, then spread the gap and filled it with resin. It worked pretty good. The 1967 Austin Texas Nationals were on a river during a Texas flash flood with logs, branches and huge rollers in the course. Jump champion Chuck Stearns won slalom, I think I placed 7th. Many of the top seeded skiers fell in the rollers . . Floods are an equalizer. When Merrill Lapoint saw my Maharajah ski, he thought the saw cut was to fix a manufacturing defect rather than to "tune" it. I declined his offer to send me a new ski.
1968 - When Dave Saucier wanted to get a skier on a Saucier ski, he would meet you at Lake Saucier in a woods in the middle of a farm somewhere. Before you ever tried the ski, he would fill his boat with white dust as he made the very large round bevels larger and rounder.
1969 - When Leroy Burnett was the slalom sensation on a wood Obrien, running 30 off (or was it 36 off ?) at every tournament, I drove to his house in Northern California to get a ski. It was the best ski I had to date after I widened the ski with epoxy about 3/32" on the good side turn from the front heal forward. Later MasterCraft-Obrien built in the same asymmetry with their La Point Radius ski, which was sold in 2 versions, for Left or Right foot forward.
Fast forward to 2021 - as an outsider trying to start over in M9 in a few months, I have the impression that sandpaper, saws, resin and files are no longer part of breaking in a new slalom ski. I just spent $1200 on a blank ski, where would I start with carpenters tools? But Finally, it looks like manufacturers have figured out that all the older skis were too narrow under the front foot. Now the top 66-67" skis (such as D3 EVO and ION) are 3/16 to 5/16" wider than the universal 6 9/16 width from the past.