If you're still progressing every week with the weight you're lifting, then it's not necessary. If not, then you need to lower the weight and start your progression again. A macrocycle (lasts a year or so) is made up of mesocycles (4-8 weeks). I set my progression so I stop adding weight (can't do any more) around 4 or 5 weeks (which will be the end of a mesocycle), then I start over. Read up on periodization