Periodization is the way training is organised for avoiding plateaus. The three parts of this include: long, mid and short term training cycles. These are called macrocycles, mesocycles and microcycles. In affect a microcycle is one week of training a mesocycle is often 4-8 weeks and a macrocycle can be any time between 3 months and 2 years (this is only really Olympians who also compete in the commonwealth games as well.) Another good example would be in seasonal team sports eg. Football and Rugby. A macrocycle would be a season and the microcycles would be: off-season, pre-season and mid season.
It’s not only athletes who should arrange their training in these cycles, it’s also vitally important in training for aesthetics. For example if you want your peak physique in time for your holiday in 3 months, you should arrange your training from that. The start of your program to your holiday is a macrocycle. Your mesocycles would be a bulk and a cut, so you can focus on building muscle then maintaining it while you aim to burn fat.
I would recommend a mesocycle lastin 6 weeks. After that I would alter my training methods. The quickest progress happens in the first 3 weeks of training, the next 3 weeks will be when the results “settle down a bit”
The main piece of advice I would give on programming is to not change your training to often or too rarely. To often your body won’t adapt to the training, to rarely and you will hit training plateaus you will never overcome. There are many people you will see in your gym who never progress in terms of performance or physique, this is because they have done the same thing at the same level consistently, for a huge amount of time. These people plateaud long ago, don’t be like them keep your training fresh and achive your goals.