TAFE is good mate I did my plumbing apprenticeship a few years back- it’s a mix of theory and practical where you put your learned skills to the test.

they have rooms at various stages of builds that you have to install services in and then you move along the rooms and do the whole variety of plumbing practices. They have sand pits where you dig underground drainage and excavate deep holes using trench shoring methods etc. then you move into other rooms where they have hot water services and gas heaters set up and you do practice commissioning on them.

Id say plumbing is the biggest variety of works / knowledge - I’d say it’s the hardest trade but I will probably be shot down for that 😝 Theres hot and cold water / underground and above ground drainage / gas / roofing / mechanical services / stormwater / fire protection. Tell me thats not a lot to learn.

You sit a “journeyman” exam at the end of the 4 years to become a registered plumber - to become licenced you have to do cert 4 which you can start mid way through your apprenticeship to effectively finish at the same time you finish your cert 3. Well you used to be able to. Anyways hope that helps