A technique I used was called "20-rep squats." It's been written about in a few places. Simply put, you choose a weight that you can do 20 squats with using good form. Next time you add weight to the bar and do 20 again, lather, rinse, repeat every week or whatever your interval is.
It works well for working out alone because the goal is simple: do 20 reps with more weight than last time, even if it's just 1 lb more. You simply don't allow yourself to stop before failure. It's "20 or die." It was the most productive form of weightlifting I've ever done in terms of increasing strength and body mass.
Many of the elite powerlifters of today squat, deadlift and bench multiple times a week, so we know that doing all multiple times in a week can be great training. But I think your conclusion is not warranted. A few decades ago, the elite powerlifters were squatting and deadlifting once a week. And they were also crazy strong.
squatting once/week is viable if you're extremely experienced and are not on steroids. The more experience you get, the more rest you need between lifts.
One of the major reasons why steroids works is because it cuts down on the required rest time by a large margin.
my coach makes me do 20-rep squats and also 10x10 with less weight once every 6 weeks or so. that's the closest i've ever come to really giving up in the middle of a set.
It works well for working out alone because the goal is simple: do 20 reps with more weight than last time, even if it's just 1 lb more. You simply don't allow yourself to stop before failure. It's "20 or die." It was the most productive form of weightlifting I've ever done in terms of increasing strength and body mass.
Make sure you have a good, stable squat rack :-)