Gotta love ruts!
Being out west and racing in ruts all the time here is how we approach it.
First, and one has to do this either by inspection during the race or pretty quick "on the fly", we categorize the rut(s) we are dealing with . We have a pretty good idea based on the snow conditions before the race what kinda of ruts we'll get and what kind of rut will develop at different gates based on the set and level of the racers in that particular race.
1) High Line Single Rut - When the majority of the racers are skiing the "good line" the rut develops above the gate and terminates just below the gate, where you'd normally exit a turn and start your transition.
Enter the rut at the highest possible point and either ride the rut with slightly narrower stance and fairly even weight bias, plan on absorbing the end of the rut as your release.
If you can enter the rut high and take the tightest line you can to the gate missing the bottom of the rut allowing for a high line release (ILE or whatever you use)
In GS either of these approaches are fairly common for the "High line rut". In Slalom, the inside wall of the rut usually falls away right at the gate, in this case Cross-blocking is not advisable, ski the rut (big ruts).
2) High line ruts with "holes". This is a well placed rut but is not smooth beginning to end. This is a skier level issue. The higher level racer will still ski the rut and be relaxed enough to "stick" their skis in the hole and use it for pop and part of the direction change. The lower level skier should probably ski the outside wall of the rut, if possible and avoid the holes if they find, during the run, that they are getting pitched out of balance due to being stiff through the holes. Relaxed skiing is the key when there are holes.
3) Low Line Rut - Providing the inside wall of the rut is not too steep, ski above/inside of the rut and be prepared to "stick" your outside foot ski in the belly of the rut. Your finish should terminate your turn above the rut exit making for a smooth transition.
4) Double, Triple ruts - This generally happens when skiers of many levels are racing on the same course. If you are unlucky enough to pull a seed and get these conditions it is again a racer level issue. The higher level racer will ski their typical line and ski very relaxed through the rutted section. The will usually look for a high line exit from the turn and make a more aggressive lateral move of the skis exited the turns (just short of a pivot as pivoting into inconsistent ruts is a typical cause of binding pre-releases). The lower level racer needs to pick a line, visually pick a rut and ski that rut as best as possible. Avoiding the lower ruts and/or chatter is a good tactical decision. A simple thought is to terminate the turn as soon as one can, anyway you can, once you get in the lower ruts as you want to get back on a high line rather than getting stuck late n' low gate after gate.
5) Chatter - Though not a true rut in harder conditions skiers who do not hold their edges will create mini-ruts fanning out away from and below the gate. Once again, not "hanging onto the turn" once in chatter is the best tactic. If you need to make a pole plant and edge set to start your new turn this is more desirable than staying "stuck" in the chatter. In other words; Get off the turning ski and into the new turn as fast and as high as you can.
Bottom line, ski relaxed, extend into the rut if its properly shaped and absorb the exit. You'll kill it
Edit - Oh yeah, avoid hitting the outside of any rut at a square angle, this is not good