I agree. The first time I pulled 500+ weighing around 170lbs at that time I was doing a Stu McRobert Brawn style program and I was squatting followed by SLDL's for 1 set only once per week. I had some cousins come in from Ohio and we started messing around with the weights and that night I hit a 485lbs squat, 340lbs bench(T-n-G) and pulled 510lbs.
This definitely stands for me. Seems like the more I deadlift the worse I get at it. Don't know if its mental or that the lift just drains my nerves. Strange enough, I also found this with the Olympic lifts. One per week of both lifts was the best for me.
On the 2xBW note...how many here have managed it double over hand grip no hook? I pulled 370lbs easily just a few weeks ago and tried 380lbs and it slipped out of my hands 3 times. I want that lift! Actually I want 400lbs+ double over hand no hook, but that may take a minute or two.
Actually this is quite common. Many do some deadlifts after a layoff, perform well, then start to train it in earnest and it goes backwards! The great Bill Starr wrote about this back in the '70's with his No Deadlift Deadlift routine where he focused on the barbell high pull barbell rows and other back exercises ( as well as squats) to build the muscles used in the DL.
this is similar to the later WSB approach. The DL is very potent medicine, a little can go a long way for some people.It's a HUGE CNS stimulant and lends itself to overtraining very easily
I'm like that for instance.
Back when I was powerlifting I could not pull 500 in the gym no matter what but pulled 545 and just missed 562 in a three lift meet
I relied on heavy squats and DL assistance exercises and just trained the DL for speed ( 70 % for singles ) and form
Bottom line you have to find out what works for you