I think it depends on your fitness goals, how devoted you are towards those goals, and how much money you are willing to spend on anabolics.
If you are just cruising or fairly casual about bodybuilding (but still workout more then 3 times per week, still eat right most of the time etc) I think high test is a great idea. It's cheap, easy, low and manageable sides, and will produce great results.
But if you are serious on day-in/day-out doing what it takes to get serious muscle growth or serious fat loss RIGHT NOW, for the cycle, you really do need to add in 1 or 2 compounds (more if preparing for an actual bodybuilding contest) in order to get the synergy of multiple compounds to produce the results.
Now, you need to have your workout regimen, sleep, alcohol abstinence, and diet and macros all absolutely dialed in for that. If you Run High test, high deca, high dbol and just workout casually, or just eat whenever you're hungry, it's not smart to run that many anabolics, because you aren't getting the positive results to outweigh the negative effects of having the anabolics in your body. The negatives will take effect regardless of your workouts and diet, but the positives will NOT take effect until you do everything right.