There is only one answer to this question and that is a resounding YES. But this does not mean there are no side effects of the same.
CAPTCHA should be placed on all parts of the website where your visitors have the ability to add content or info – comments or webforms. The goal of this is to minimize the bots (i.e. computers) from generating meaningless comments or web form entries. This will make your webmaster’s or marketing manager job easier as they will not spend time on reviewing loads of entries that are effectively spam.
One benefit is often neglected and it is related to your email server. In this scenario, your website webform is set so that for each submission you shoot out some welcoming or registration email to the visitor that used the web form. This means that your email server will start generating large numbers of emails that often are not deliverable or are simply excessive in numbers. This then may result in your mail server getting blacklisted or blocked…and a company today can’t really function with blocked emails.
Here is where CAPTCHA again comes to play and prevents this whole scenario from happening!