Your problem with edge joint failures does seem to be a bit of a mystery. Assuming all else is correct, e.g., the edges marry up seamlessly I now can only think of two things that might be the cause, whilst also discounting the type of adhesive used, whether it be PVA, aliphatic resin, hide glue, urea formaldehyde, etc:
1. A bad batch of adhesive. This is possible; I've experienced it two, three or four times over the years with a couple of adhesive formulations. In my experience a bad batch of adhesive is extremely rare. But your report of (seemingly) fairly regular glue joint failures of one sort or another with your employer's projects does rather make me wonder why that is the case, even though you offered possible causes, e.g., wet wood and shrinkage coupled with 'poor' adhesive.
2. I do also wonder about your adhesive application procedure. PVA and aliphatic resin emulsion types generally require swift adhesive spreading followed by rapid application of pressure to create a strong bond. Like you, I quite often apply the adhesive to both surfaces of a joint, whether they be edge joints or other types, e.g., M&Ts, biscuit, dovetails, etc. But I get the stuff on as fast as possible, and aim to have the joint clamped up within five minutes or less, from the time I start applying the adhesive until the time I'm done.
Whilst I recognise the problem you're trying to avoid, the dry spots you mention, this seemingly double application procedure you undertake I suspect adds time to the job, and I wonder if what's happening is the first application of adhesive is partially cured before you can get your secondary infilling application in place, and the job clamped up, which can, or could, lead to a visible thickness of glue line. Visibly thick glue lines are a weakness. I can't recall the exact numbers offhand, but to create a strong glue joint with the emulsion glues you only need a film of glue between the wood parts somewhere in the region of three molecules thick, which is too thin to see with the naked eye. There is some very shallow absorption and incorporation of glue into the wood grain on either side of the joint, which is also a requirement for a strong joint.
So, perhaps the answer to your problem might be to just get the adhesive on quicker in the first place, and get enough on to prevent these 'dry spots' you describe even being a possibility, followed swiftly by clamping the job up. Slainte.