Well, it depends how much you care that your talk was a disaster.
For people who are not practised at speaking, there is almost no amount of preparation which will get you to the point of needing no crutch. Not knowing your subject well enough is not excusable, but many people who can happily explain a topic in a one-on-one situation have great difficulties in front of crowd.
Of course, there is only one way to get better a public speaking, which is to do as much of it as you can.
I don't understand your 'teacher-student environment' comment. Are you suggesting 'coddling' encourages, or discourages, giving talks with less crutches?
For people who are not practised at speaking, there is almost no amount of preparation which will get you to the point of needing no crutch. Not knowing your subject well enough is not excusable, but many people who can happily explain a topic in a one-on-one situation have great difficulties in front of crowd.
Of course, there is only one way to get better a public speaking, which is to do as much of it as you can.
I don't understand your 'teacher-student environment' comment. Are you suggesting 'coddling' encourages, or discourages, giving talks with less crutches?