Gray Cook has written "Maintain the squat. Train the deadlift" and it is sage advice for some people. For others, it is NOT.
I believe that there are three kinds of people who deadlift:
*Those BUILT TO DEADLIFT
*Those NOT BUILT TO DEADLIFT
*Those BUILT TO NOT DEADLIFT
If you are "built to deadlift", you probably have a short torso, long arms, big hands, short femurs. You can follow Ed Coan's training template. You can deadlift heavy once a week or more. You will make gains. Progress, while it may slow, is steady and reliable. You laugh at powerlifting competitions as you pass your fellow competitors by a hundred pounds or more in the last pull of the meet.
If you are "not built to deadlift", you are not built to be a superlative deadlifter, however, with intelligent effort, you can be formidable - your deadlift may very well become a strength. Most people probably fall into this category.
Those who are "built to NOT deadlift" (long torso and femurs, short tibias and arms) will quickly overtrain or injure themselves if they deadlift heavy with any kind of frequency. For people like this, they would be better off training their squat and doing supplemental work in the form of good mornings, box squats, and Romanian deadlifts as tolerated.
I'm built to not deadlift. That's not an excuse - that's a reason. Doesn't mean it's an excuse to be weak-sauce - just that training should be adjusted accordingly.