IN material handler why they are using 3 section telescopic boom instead of 4 or 5?

Number of factors can be accounted. like

1. Maintaining strength by reducing the number of telescopic booms (Less elasticity)

2. Higher the number of booms , will lower the carrying capacity

3. Safety while loading & Travelling

4. More Hydraulic (Flow , Pressure and Internal circuit) will be required for telescoping functions

5. For Higher reach , cranes are already available for the purpose for more telescoping extensions