Considering that public speaking heads the list of all phobias, the reasons people register for a course is usually out of necessity, i.e. they have been promoted at work and now have to chair meetings and deliver speeches, or they might just wish to improve their self-confidence in public, which is, after all, the purpose of such courses.
One student at a night school, in Sydney, revealed in the first lesson of a 6 week course that he was to be married in two months' time, and he didn't want to disappoint his bride and the wedding guests by delivering a poor groom's speech.  He also said that he felt obliged to deliver a funny speech despite the fact that he wasn't a funny man.  My advice to him, as usual, was to forget being funny and to speak from the heart.  He spent every lesson perfecting his speech.
In the last lesson he delivered the speech he intended to give two weeks later.  His opening remark was quite funny:
"I looked up books of quotations on marriage, but I couldn't find any that were in favour of it!"
The rest of his speech was deeply touching and earned him a standing ovation from the class.
I said to him after the class:
"You really must tell your bride about doing this course."
He insisted that she must 'never know', to which I said:
"I can't think of a more thoughtful compliment to pay a bride than her nervous husband-to-be attending a public speaking course, to give him the confidence not to disappoint her at the reception."
He shook his head, but I urged him to tell her, if not on their honeymoon, then in the near future.