Does the type of substrate chosen (clay pebbles, rockwool, coco fibre etc.) change irrigation times?

Yes, of course. There are three mayor types of substrate: those which retain moisture, such as coco fibre, draining substrates, such as clay pebbles, and water, the hydroponic substrate par excellence. Depending on the water retention capacity of the substrate, the time period for which it is necessary to stop irrigation will be longer or shorter. For example, with clay pebbles, you should keep your pump on all the time, whereas you will need to stop irrigation at times with rockwool and coco fibre. Use a timer to make this easier.