I’d be interested in what virtually guarenteed looks like. Something like: most folks will be 10-20% stronger or lift at least 50lbs more on the deadlift than 5/3/1, give or take.
I don’t disagree that practising the movement is the best way to get better at it though. That’s how people have peaked for decades but it’s also why statements about fastest progression needs to come with a timeframe.
For example, a newb come in and pulled 205kg after 3 months at the gym I’ve been going to for the past bit. Block periodisation kinda deal with compounds, assistance and isolation work in various rep ranges. SS, for example, would likely have had him pull 170-180kg (+55kg training, accurate-ish 1RM estimate and say +20kg [15%] peak, assuming no stalls and a decent peak as SS gives you 1 day off as a peak) in that same time.
I also have zero doubt that at the 1 or 2 month mark SS would have had him doing a much bigger pull. So time frames matter.
I have my thoughts on why this is and why moving programs at 2 months fails for a bunch of people
(especially if they stick to 3 stalls/resets) but I was only a mediocre strongman and an even more mediocre powerlifter. And the standards today are WAY higher than 7ish years ago when I last graced a platform, especially with raw lifting.
I was also more keen on sharing my experience of 5/3/1 keeping me injury free and adding some poundage to my maxes after a long layoff than justifying why I didn’t choose LP for myself but I am happy to share my thoughts if you’re interested.
That said, I’ve seen @dt79 and @T3hPwnisher who are more accomplished than me (currently ) recently post about strength gain vs technique improvement so you may be better hitting them up/reading their stuff.