Pocket hole or traditional joinery is one of the few subjects in woodworking that can get some of the most mellow mannered woodworkers into serious debates, and it is something I do get asked about now and then. Always looking to avoid the debate that will certainly follow I have become really good at just avoiding the question over the years. But after giving it some thought I felt it was time to share my thoughts on the subject, whatever they might be worth. Now I'm not writing this as some sort of bible all who woodwork must kneel before, it's nothing more than my personal opinion and as such you have the right to disagree with me it is a free world.
The only problem I see with pocket screws really falls on one factor, wood movement. By nature wood expands and contracts due to changes in temperature and humidity created by seasonal changes, a pocket screw being made of metal is not effected by seasonal changes. So initially when a screw is driven in to the wood it is nice and tight, but when the wood expans from seasonal movement the hole that the screw is in expans with it and is now too big for the screw causing a loose connection resulting in a faulty joint. Is there a way to prevent this ? No. Is there a way around this ? Yes, using a plywood because plywoods are not as effected by seasonal changes. For me I build furniture and the choice of material for whatever I'm building is usually at the heart of it's beauty so I would never considering using any type of a plywood product, but it really comes down to what your motivations are with what you build. Are you looking to build something quick that does the job or are you pushing yourself to create something better than anything you have built before. With me it is always the latter never looking back at what I've done, build it once build it right then move on to hopefully build something greater. Just sharing my thoughts but for these reasons I do not use pocket screw joinery, besides it's hard to create joinery like this with pocket screws and plywood.