I do a lot of disavow work. But, I don't recommend disavowing for everyone. Here are the reasons why I *would* recommend disavowing links:
-If the site has previously been involved in building their own links. Even if you've done a disavow, new links will continue to appear.
-If there is obvious evidence of negative SEO or links because of pharma spam.
I don't recommend disavowing for sites that seem to have the occasional spammy looking link in the profile but don't fit the above criteria.
If you look at the backlink profile of almost any site you're going to see links that look spammy. Google will not penalize or algorithmically demote for those. Penguin was designed to demote sites that are actively trying to cheat the system.
I have seen no evidence that Google uses the Disavow Tool as a part of their algorithm. I also have not seen any case study that show were only using the Disavow Tool improves a penguin penalty or improves rank.
I've seen plenty of sites improve by using the disavow tool and yes, I've seen Penguin recoveries with disavowing alone. I currently don't recommend actively doing link removal for Penguin unless you have links that you can easily remove. Here's one example of a lawyer's site that had a lot of spammy links. They were hit by Penguin a couple of times. Their links would have been impossible to remove so we disavowed. They saw a nice recovery with the Penguin refresh of October 2014 and they now hold #1-3 positions for most of their terms:
This site has done no additional link building. But they do attract links because they have a good site. They used to rank mid to bottom of page 1 after getting hit by Penguin and now after disavowing and waiting for Penguin to refresh, they have excellent rankings:
That type of recovery can happen, but it's not super common because many of the sites that got hit by Penguin never deserved to rank in the first place so once those spammy links are disavowed, there's nothing there to hold up rankings.
The problem though is that there is no way for me to prove that this site recovered without us removing links. Any site that has spammy links will show link loss when looked at on a tool like ahrefs, because spammy domains die. But, I've yet to see a site that recovered from Penguin by doing nothing. If losing spammy links because a bunch of them died were enough, then we should see spontaneous Penguin recoveries. In this case (and in several others that I have) we disavowed only and we still continue to disavow any old remnants of spammy links that pop up to this day.
But back to the original question - Do I regularly recommend disavowing for all clients? I do think it's a good idea to spend some time each month perusing the backlink profile but unless there is an obvious influx of links or a history of past spam, then no, I do not do this regularly.