That's some good advice and drills to practice. If you have been studying, you have probably learned what I have to say. Maybe even seen pictures.
The front sight when shooting iron sights, is the most important step in sighting. Stance, grip and trigger press are just as important. Trigger press without the sights moving off your point of aim is just as important, stance and grip can be more lax, but it depends on what you want.
1) Target accuracy.
2) Self defense accuracy, you don't have to be an X ring driven shooter to protect yourself.
I have taught a lot of handgun classes, and this is my explanation of sight picture. 1st the reason the front sight is the most important. The human eye can only focus on one object at a time, since the front sight is closest to the area the bullet will exit, it has the most influence on where the bullet will strike downrange. If you focus on the target, you might as well not have sights as you not using them anyway.
Lets suppose your sitting at the breakfast table and looking out the window which is open, and see a squirrel on the trunk of the tree, the squirrel is your main interest so your eye focus is sharp on the squirrel, at that point your not aware of the window anymore, and human nature when it comes to looking a things through portal, like a window is to center the object in that portal, that explains rear sight, ( window ) front sight ( squirrel ) now to the target, the tree, if you shift your focus from the squirrel to the tree, your aware of the squirrel, but do not know absolutely where he is.
So FWIW, look through the window ( rear sight ) at the squirrel ( front sight ) and place that crystal clear squirrel on the tree, ( the target ) where you want him to be. Then press the trigger without the squirrel moving to another spot. X ring.
But a couple of questions, how is your eyesight? Do you wear corrective lenses? The lesson shifts if you cannot focus on the front sight like me now, up until I was 40 my eyesight was exceptional, as it deteriorated, I could not focus with my glasses on but could without my correctives on, so I just wore, shooting glasses, through the years, it has deteriorated more and I can still the front sight clear, but the target is very blurry, so I have to do a shift, front sight close to where I want to hit, shift to target for a reference, shift back to front sight and press. For self defense distances, this is not a problem. For competition I now shoot a red dot, and on my iron sight gun, fibre optic front sight and a wide 1/8" notch in the rear sight, it works and I can still hit, I just miss the picture I used to see.
Hope these explanations and previously mentioned drills have helped.
Good luck.