For full length PTs, I like the questions to all be new, but honestly, I like to redo questions. If it's been 3+ months since I last saw a question, I usually vaguely remember the topic (especially RC passages) but I rarely remember the correct answer. Additionally, going back through and redoing every question I've gotten wrong has been super helpful, because it's the easiest way to automatically target your weaknesses. As you know, 7sage has lots of helpful filters that have made it easy for me to go back and redo questions that I either got wrong the first time or just did a long time ago, and I feel like I still benefit from this practice.

I agree with the people on here saying that working full-time makes it easier to study than being, for example, a college student. The structure of having the same hours every day really helps establish a solid study routine. As soon as I get home, I go straight to studying for two hours before I do anything else. Having a rigid routine and a predictable schedule makes studying feel less like an impending chore that I want to avoid and more like just another part of my day. (For those with variable work schedules and odd hours, I've got nothing. Sorry, that must be very difficult.)

In my experience, the best way to specifically train stamina is simply volume. Just like with running long distances, the best way to not get tired with a set quantity is to practice at about 1.5-2x that quantity. If you're trying to run a 5 mile race, make sure that you occasionally run at least 10 miles in practice. If you're trying to take a 4-section test, make sure that you, at least occasionally, take 6-8 sections in a row. (Source: I took the LSAT just a few months after I took the MCAT, which is an 8 hour long test, and the LSAT felt like a breeze in comparison, stamina-wise. Now that I'm studying to retake the LSAT over a year later, I've been struggling with stamina as well because I haven't been practicing at the same level of pure volume like I was when I studied for the MCAT back then.)