No, laser epilation is not done every week. It is usually applied at intervals of 4-8 weeks. The reason for this:

Hair Growth Cycle: Laser epilation is effective in the active growth (anagen) phase of the hair. Since not all hairs are in this phase at the same time, the procedure must be performed at certain intervals.
Skin Sensitivity: Sufficient time should be left between sessions to prevent skin irritation, redness or sensitivity.
Getting Effective Results: Frequent sessions do not increase the effectiveness of the laser. If it is not applied at the right time, the probability of catching the hairs in the appropriate phase decreases.
Session intervals may vary depending on which area you have laser applied:

Face area: 4-6 weeks
Body areas: 6-8 weeks