Shedding and Trimming Plants Plants the 3rd - 5 Weeks

My plants are growing well. However, as they grow thick, is it advisable to trim them!

Yes it is. If you have very thick growth and you don't defoliate you'll run into trouble on week 5-6 of flower. Too much foliage makes it impossible for light and airflow to get around your buds.

I don't worry about much defol in veg, I more concentrate on plant training and root development. Then on day 1 of flip do a hardcore leaf strip and then same again at the end of week 3. Don't touch them for the rest of flower. You will be amazed how much difference this technique makes to your final yield.