Idea thats been around since Paul Anderson days. He would do a set ever hour or two all day but NOT too failure. Also more recently Pavel Tsauloune (no idea how to spell) wrote about it many books. Not really for hypertrophy more for improving neurmuscular coordination to improve lifts not really muscles. Pavel calls it greasing the groove.
Paul Anderson would train 3 sessions daily x 6 days per week for a 1 - 3 rep working set in each exercise. M, W, F were clean & jerk, clean & press, and snatch plus assistance exercises targeting the upper body. T, R, Sa were squats and variations (1/4 or 1/2 squats).
A sample training block for Anderson:
M, W, F:
Press 145 kg x 2 set
Dumbbell Press 61 kg x 2 dumbbells x 3 rep x 2 set
Snatch 1 rep up to 140 kg
Clean 1 rep up to 182 kg
Deadlift 313 kg x 3 rep x 2 set
High Pull 227 kg x 3 x 3 set
Ad hoc Bench Press up to 200 kg
T, R, Sa:
Back Squat 295 kg 1 - 3 set x 2 rep, 3rd session up to 309 kg
1/4 & 1/2 squat variation up to a claimed 713 kg (unlikely)
In line with what you and others have mentioned: though sub-optimal, this training style moderates volume but maintains intensity, serving to maintain and push up top end strength and inter- & intra- muscular coordination for highly coordinated lifts.
Very sub-optimal for hypertrophy (see: Bulgarian weightlifters, Paul Anderson physiques, for examples of mediocre hypertrophy vs. bodybuilders). This was done back in the 1950s in Anderson's case and in the 1980s under Abadjiev in Bulgaria: aside from serving these goals (coordination, strength) it also served to keep the lifters from chasing tail, boozing, and smoking heavily. It kept them out of trouble.
Pavel promotes high frequency training for maintaining and pushing up inter- & intra- muscular coordination for highly coordinated lifts like the kettlebell snatch, and ramping up sets/volume to promote increased muscular endurance, as these qualities are necessary for Russian kettlebell competition (see also: Pavel's physique, for an example of muscular endurance vs. muscular hypertrophy).