Yes. It is important to build up, in intensity, in volume, in both (depending on the phase objectives).
But it is also very important to have small weeks.
A group of weeks (microcycles), is called mezzocycle. Some also call it macrocycle. It can consist of 3 to 6 weeks. Often 4. Sometimes 8.
Given you use 6 weeks mezzo. You can go
w1 : medium
w2 : hard
w3 : ez
w4 : hard
w5 : very hard
w6 : very ez
Sessions are part of a week. Weeks are part of a mezzocycle. Mezzocycles are part of a phase. Phases are part of a year. Years are part of a multi year plan (e.g. 4 years at the time, in the case of an Olympic Athlete).