Watching the better VP4 players play rotation style games like 9-Ball or 10-Ball, I see a deficiency in kick shots compared to Real Life (RL) players of the same level. Kick shots are very important as they come up often when snookered. The first goal when snookered is to hit the ball so your opponent does not get Ball In Hand (BIH). But you can do better than that, by being able to kick at balls and direct them with line and direction so you get safe, possibly even snookering your opponent. To do this you need to be able to at least pick the half of the object ball you want to hit, better accuracy makes better results. This applies to all kick shots. Obviously, single rail kicks are easier especially with the object ball close to the rail. 

Multiple rail shots are much harder to determine the cue ball line because English changes the line. There is almost always English on a multiple rail kick because the cue ball picks up running English off the rails. When the cue ball has running English the line off the rail is opened up to a larger angle. How much it opens depends mostly on the amount of English the cue ball has and the angle of incidence (angle into the rail). Also adding to the puzzle is how the cue ball is struck. Running English is the most common addition, that changes the path potentially off both the first and second rails.

Getting better requires practice. One way to do this is to set up kick shots with VP4 Offline and hit them over and over till you understand the path and speed needed to get the object ball to move the desired direction and speed. Another way, possibly more fun for those of you who don't like to practice, is to play Three Cushion Billiards. 
Note that there are many rail systems to assist you with learning multiple rail kicks. You don't need them, most great Billiards players do not use them. But they can be a helpful reference and learning tool.