Yes but after Stan trained with Flex and won his pro card he went to Supertraining gym with Mark Bell.
Where all he did was squat and deadlift with low reps/singles and low volume. He went on to win a world record total in power lifting. This was done back to back and Stan was in his mid 40's.

Stan is a brilliant person who has an unbelievable hard work ethic since he was a child. He is also a very successful and wealthy business man.
For some true wisdom go to his you tube channel and watch his "Rhino Rants."

I do two a days like this. In the morning I do heavy loads like 5x5 or 3,2,1 ect. I go as heavy as I can with plenty of rest in between sets and keep the session short like 45min. All big compound movements only. The big basics. Then at night I do mostly assistance work and chase the pump. Isolating single muscles and putting them under tension for as long as possible until I completely burn out. The first season is heavy more for cns stimulation and strength. I don’t usually go to failure on these sets but I push as heavy of weight as I can and use progressive overload. The second round is to get blood and nutrients pumping into the muscle again and to make sure I’m getting all the smaller muscles fatigued as well. In order for this to be effective you need to to eat enough and get plenty of sleep. I take a short nap 30 min after my post workout meal and sleep at least 9 hours a night.

4 days a week I’m there for about 1:15 mins then once a week I’m there for about 2 hours maybe a little longer I do feel shorter training periods are better twice a day seems excessive to me unless you have the spare time

I train 30-45 min. 30 sec breaks and lots of supersets.

I would change my routine mixing in all aspects of what you mentioned. That way you confuse your body and can break plateaus and achieve maximum results!

Levelup got you some good points below, regarding how to incorporate NOT squatting or deadlifting should be pretty straightforward, just don’t squat or deadlift...

Wiseassery aside, I do the same. I work around my lower back and spend time focusing on time under tension and controlled leg pressing with different foot arrangements to target different parts of the leg. Then accessory isolation movements to burnout those groups.

I feel like my legs have been making progress but I also feel like my back has just never quite been the same as when I was consistently deadlifting or at least rack pulling 500+ It’s hard to recreate that stress with rowing movements.

Have you hit a point where you aren’t progressing?
The point of two a days is being able to bring peak intensity twice a day...I think for most people the struggle is to bring peak intensity once a day.
Try taking main movements to two all out working sets to failure(rest/pause, drop, etc) second set could be a little bit of a back off set from the first to maintsin max effort...not spending so much time on metabolic/pump work but focus on progressive overload and maximum expenditure within your working sets.