There is potential harm. Webform inquiries get added to your file and they MUST look at all the webforms before taking any important steps on the file. You wouldn't want them to refuse you because they didn't read your webform, right?
Well, when an officer has a free half hour and wants to complete something (because, like anyone, they know if they can't finish and have to return to it later they have to start over AND there will possibly be more webforms), which one will they pick 'at random' from their inbox - the super-thick file with dozens of webforms or the thin one?
Don't get me wrong - do webforms for important communications, corrections, etc. But sending them frequent webforms quite possibly will delay processing of your file. And of course, webforms that amount to "hey what's up with my file" actualy serve very little purpose and are not going to get any kind of response except an automated or form letter. (Subsequent inquiries of substance will be more likely to be ignored too)