I'm curious what research you've done on DeMartini's method? Have you taken any of her courses? Or have you read her book?

From what I understand, you return to your dog when it shows signs of distress.

It's been a few years since I've read DeMartini's book, but from what I recall, this is not the correct usage of her method. You return to your dog before they exhibit signs of distress, and you increase that time little by little on a variable schedule, slowly building their confidence that you'll always return. This teaches the dog to self-soothe and eventually become more independent. If your dog begins to cry or bark, you've gone too far, and you need to reduce the time you leave the dog alone and rebuild that threshold again.

If a dog is whining or barking, you need to understand the reason or function of that behavior. If the dog is making a ruckus specifically for attention (And this applies to most attention-seeking behaviors), then, yes, ignoring the dog is best. This teaches the dog that his behavior will not give him what he wants.

However, if a dog is whining or barking because he is legitimately stressed or afraid, ignoring him will not solve the issue. A dog diagnosed with true separation anxiety is flooded with stress hormones when their guardians leave, and they are living in a state of fear or anxiety while they are gone.

So, the cry-it-out method, even with human babies, is actually quite controversial. I'm not an expert in this field by any means, but my understanding is that for very young infants, the cry-it-out method is not recommended at all, and for a lot of parents, it may even be falling out of favor--of course, there are nuances to this as discussed above. Is your child at a stage where they simply need to learn to be more independent and self-soothe? Or are they still very much wired to need parental attention/affection and ignoring their cries can pose developmental harm?

Think about it this way: As far as separation anxiety goes in dogs, treat it like a phobia. Dogs who suffer from SA are legitimately afraid of being left alone. If you were deathly afraid of water or spiders or heights, would it help your phobia if someone pushed you into a deep pool or dumped a bucket of spiders on you or forced you to go bungee jumping? Of course not. In fact, it would probably make your phobia worse and diminish your trust in whomever forced you to overcome your fears in an unhelpful way.

I recommend you take a look at our Wiki on Separation Anxiety to further address your questions. I am also linking DeMartini's FAQs for you to peruse--her book is quite good, too, so if you're interested in applying her methods, I think making that small purchase is an excellent investment.

Hope this helps!

Read this book cover to cover: Treating Separation Anxiety In Dogs https://smile.amazon.com/dp/B08D4SX4DP/ref=cm_sw_r_awdo_MG76H85SJBXB1KVGDP68. It's how I was able to treat my dogs separation anxiety to the point where I could leave her alone for a full shift of work. The biggest thing I found, especially early on, is to be very consistent, establish a daily routine of exercises, and do your best to never go over your dogs threshold.