supersets and dropsets are two tools that suit the same purpose : getting more workvolume in there.
They are a great tool to improve muscular endurance and growth.
Supersets are ideal for supporting excercises and isolation excercises
dropsets are ideal for big excercises, preferably compound, to get more volume and get more then once to musuclar failure
Supersets
I for example used to have difficulties locking out deadlifts above 230kg. I used to have difficulties with my squatform above 180kg due to hamstrings beeing far to weak in comparison to my massive quadriceps.
My big muscles were fine, but several supporting ones needed to get alot bigger. And you cannot directly put huge pressure on them cause they cant handle it. You need to increase volume, but without adding a to big weight, and without making the weight insignificant.
For 10 months i've run a schedule that had nice volume (week1 : 5x5, week2 1x5, 3x2, week3 : 1x5, 1x3, max repsx1, week4 deload and repeat) on the big excercises, coupled with many supersets such as :
leg curl(12reps) with leg extention(12rep) superset, 3 sets, 90sec break
hanging knee raise(20speedreps) with hyper extentions (20rep) superset, 3 sets 60 sec break
dumbell military press(8rep) with barbell row (12rep) superset, 5 sets, 120sec break
read deltoid flies (20rep) with barbell shrugs (20reps) superset, 3 sets , 60 sec break (this one is a killer)
side lateral raise with cable(15reps) with low cable face pulls (15reps) superset , 3sets, 60 sec break
bulgarian split squat (12 reps) with dumbell walking lunges(12steps) superset, 5 sets, 90sec break (this one downright kills you)
sit ups (12) with calve raise(30rep) superset, 5 sets, 30sec break
flat dumbell bench press(8rep) with chest supported rows(12rep) superset, 5 sets, 120sec break
swiss bar curls(12reps) with close grip bench press(12reps) superset, 3 sets, 60sec break
easy cable reverse curls(20reps) with cable pushdown (20reps), 3 sets, 60sec break
Dropsets
Dropsets are a great way to deal with muscle fatigue in the bigger lifts, and get more reps beyond first failure, to get more volume in there. Its aslo excellent for the neural system to deal with the movement and keeping form right.
In the previous schedule, i allready had plenty of volume going, so i couldnt add dropsets there. However, after the main excercise, there was twice a case of a strong excercise that could preferably use dropsets
These were Wide Grip Lateral Pulldown, and Decline Leg Press. One trains the entire upper back primarly, and the sides and upper arms secondary.
Leg presses work on the entire leg, and if you go deep enough, also the glutes.
In my current schedule (reactive training with twoblokperiodisation) i alternate 3 weeks of volume work and 3 weeks of intensity, based on "rate of perceived exertion" or RPE
The RPE basically says how many reps you got in the tank. I'll list the 3 that matter
RPE10 : 0 reps left after
RPE9 : 1-2 reps left
RPE8: 2-4 reps left
So what i do is for example 6reps@RPE8. Wich means i seek the weight i can do for 8-10 reps, but i only do 6. my schedule then demands me to keep doing 6reps with 90sec breaks. Because of fatigue, it will get more and more difficult, untill the 6 reps are an RPE10.
As you can see, RPE is a way to train based on how you feel that day. Lineair progression has the flaw that if you didnt sleep well, had sex several times before training, didnt eat well, didnt drink well, ... that you might fail sets cause you arent at your best. RPE basically tells you to chose the weight depending on your form that day.
In the first week, thats enough. In the second and third week, we want to make this more heavy, more volume. But because its RPE based, we cant just add a weight, cause it defeates the purpose.
What we do instead, is use dropsets. With an excercise, when i went from6reps@RPE8 untill 6reps@rpe10, i lower the weight 5%, and repeat the excercise untill i hit RPE10 again. In the third week, after that we lower an additional 10% and take that till RPE10.
Its very handy to get extra volume in.
This is the powerlifting way of dropsetting however. after muscular failure, lower the weight and go to next failure.
if your only goal is bigger muscles, then there is bodybuilding way of dropsetting. Basically means that you do a number of reps, quickly deload some weight, and repeat the number of reps, deload again and repeat the number of reps again etc. This doesnt build power, but it builds endurance and size in the muscle.
But use dropsets only on the big muscles.