As mentioned in This Post for myself the number 24 (3 sets of 8, 4 sets of 6, even 12 sets of 2 etc.) represents a perfect number in regard to optimizing exercise volume & intensity.

Frequency of training is another important component—especially for the natural trainee, and is determined ultimately by the aforementioned level of intensity.
There is a finite level of intensity that a trainee will reach before they see some regression. Sustaining upper-level intensity can only go on for so long.
In the past with my own training, I would almost always take each set to at least positive failure (sometimes beyond if I had a training partner or a spotter) and while this style of training certainly sends the brain signals to increase strength & size, it also can quickly and sometimes abruptly fry your CNS (Central Nervous System.)—possibly causing a plethora of negative outcomes (injury, illness, negative hormonal response etc.)
I used to judge a workout mainly on how sore I was the following day(s) but now am not so sure that soreness is indicative of progress at all.
For example I have been doing exactly three exercises for the last few months and am never sore despite making progress strength-wise on all three lifts.
If I were to say decide to throw some in some deadlifts into the mix, even though quite a few of the same muscles are utilized in squats that I train four times a week, I would probably wake up the next day with some minor soreness in the traps, but this soreness would be short-lived if I continued to perform deadlifts in the manner I am currently doing the dips, chin-ups & squats (high-frequency, low volume, progression through periodization.)
A popular notion in bodybuilding magazine workouts is to base training on specific body-part splits, hitting one area/part per day with extensive volume and oftentimes high intensity (i.e. Monday-Chest, Tuesday-Back, Wednesday-Legs, Thursday-Shoulders, Friday-Arms etc.)
While some have had success with this approach, I believe a better pathway to progress for natural trainees is to curtail the volume and increase the frequency in which you hit specific areas.
Full-Body Workouts (3 times per week.)
Upper/Lower Splits.
Push/Pull/Legs.
Etc.
All of these, have you working specific areas with increased frequency and the programming for each is way more optimal for natural trainees in my opinion
John