It depends what you are trying to edit.
Are you thinking you may move, or change jobs, or something else, after you apply? If so, you will be able to update any future changes to your situation to IRCC, and it's not an issue.
I would not rely on being able to change things if you've made a mistake. You should check your application very carefully before you submit it to make sure it is accurate. In the best case, yes, if you make a mistake IRCC may be reasonable an accept an updated document. But in the worst case, they may reject your application, possibly after a long wait, and you may not get your fees back, which is over $1000 CAD. Or even worse, if they suspect you of lying on purpose to misrepresent they can bar you from applying again.
So yes, some people have fixed errors they made, but it's better not to make them.
