To get the most out of your training you should use training cycles for a specified period of time. A training cycle usually means doing a prescribed number of exercises for a set number of weeks using a specified method of training.
Elite (world record holders and world champions) athletes may have a training cycle of two weeks although this is rare. High-level athletes usually have a cycle lasting 4-6 weeks. The higher the level of the athlete the shorter the cycle may be. Beginners and novices however, usually have a training cycle that lasts 12 or more weeks.
Each training cycle ends when you have achieved the most that you can from each exercise. In other words you should have appreciable adaptation which then allows you to tackle the next cycle. The training in one cycle should lead to a sufficient level of adaptation (development) which allows you to do the work prescribed in the next cycle.
Keep in mind that each consecutive training cycle is usually more voluminous, difficult, intense or a combination of one or more of these factors. In addition, each new training cycle should have an element of novelty. This means doing new exercises, using a different training method, or previously used exercises executed in a different manner.
Rather than using the above-described training cycles, which are most productive in relation to gaining strength, speed, mass, etc. many teams use cycles or blocks. These cycles use the same exercises in basically the same manner but with different weights. The only thing that changes is the emphasis on strength, power, mass, etc. which is supposedly gained by manipulating the amount of weight.
These programs typically lead to very slow increases in the physical qualities being sought. The gains may be rapid when first starting but get slower the longer the athlete stays on the program.
To not fall into this slow gains-stagnation pattern, structure your training cycles according to the guidelines that have been outlined above. It is not hard to construct such effective training cycles but it does take a little imagination mixed in with scientific principles of training.