Yes.

The number of steps in Manufacturing can be changed at any time - always working forward - meaning the change will come into effect on the NEXT Manufacturing Order(s).

You can change at any time, or even enable all three* and configure Odoo to use one option per Warehouse, Product Category or Product.

*to enable all three:

• configure for 3 steps
• duplicate the 3 step Route
• configure for 2 steps
• duplicate the 2 step Route
• configure for 1 step
• rename Routes as needed
• set them up to be selectable on the Warehouse, Product Category, or Product

Note that if you ever select multiple steps on a Warehouse / Category / Product, Odoo will choose the highest in the list of Routes (you can drag Routes in the Routes Menu, Odoo starts from the top and works down until it finds the first Manufacturing Route if you have multiple options selected).