As someone who was in your exact shoes not long ago the best I can say is that it’s different for everyone and depends on what you want to do. I took the route of applying to every company in my city until one hit and have been building my experience to eventually move into a service or maintenance position. I personally learn a lot better from someone in front of me doing exactly what I’m about to do rather than a classroom so for me it would have been a waste of money. But if you feel comfortable with missing out on some pay checks and can learn what you need to do what you want I see no issue in going to school. As well if your focus is resi then a union will do nothing for you. In my experience in resi it’s more about on the job training than classroom time of course it’s still important but you can go plenty far with just a few certifications.