I would say the most dangerous thing for a ski tune is over reliance on machinery, coupled with a lack
of attention/understanding of how they work.
In our area, shops have purchased specific base beveling machinery. Through either a lack of understanding or
attention we have seen a number of skis with too much base bevel.
This means we have to grind the skis flat (or flatter) to reset the correct bevels.
It is for this reason that our shop has only finished skis with SVST guides. Though using hand tools is more
time consuming, and pretty exhausting when you have many pairs to do, it provides accurate feedback to the technician
about what is happening with the ski.
There is also a reason only the more experiences techs work the finish bench in our shop, it takes a while for newbies to
figure out when a file is clogged vs. when the desired angle is reached, what a hanging burr feels like to the touch and how
to remove it, and when and how much detuning is needed.
I personally do grind, then side edge, then base edge, then wax. It is not unheard of to pass a ski once over the stone at the slowest
feed speed to remove metal shavings or marks made by the bevel guide, it is faster than base tape and doesn't change the bevel
If it is a prepped race ski, then base tape, because you don't want to undo the hours of waxing that have already gone into the ski stone grinding.