The advantage of training through a formal institution is specialised teaching in each area you learn about. The avg church size in Australia is under 100 so often there is limited options of being trained in anything let alone everything you want to be trained in.
A large disadvantage of being trained by the local church is the amplification of false beliefs. With no other opinions than the lead pastor - who is to verify if what they teach can be trusted. This is a fast track to cultish tendencies.
I recognise Jesus wasn’t a registered training organisation and mentored the disciples Himself- but there knowledge of Scripture going into the training probably exceeds most degree level pastors coming out of training.