A lot of the commercial gyms I used to go to before opening up PTC used to only have 1.5kg plates as the smallest increment. No fractional plates of the (0.25kg/0.5kg/0.75kg/ 1kg) kind lying around that I could remember.
The problem this creates is u cannot sustain an increase of 3kg per week on lifts such as the overhead press/bench press or Barbell row. Reason being these lifts use much smaller muscles then what is recruited in the squat and deadlifts for example.
The general way to get around this is to deload much more often than expected and work your way back up to break through these numbers. This of course gives an advantage to the ones with access to fractional plates whom can keep trucking on.
Bodyweight and fractional plates
The smaller you are in structure/bodyweight (example 80kg) your numbers increased weak and in and out will be slower than somebody whom is (130kg+) and can get away with them using the 1.5kg-2.5kg weights as they have bigger muscles and better leverages.
Let’s compare average percentages of weight lifted here to get another picture.
An 80kg lifter whom squats 120kg adding 3kg to their max equals 2.5% to the
a 140kg lifter whom squats 240kg adding 3kg to their max equals 1.25%
The percentages are even worse once u throw it into the press equation.
As u can see if you’re a smaller and weaker lifter you’re at a disadvantage until u get much stronger.
Some people would scoff at the idea of using such small weights in their programming.
I have beginner females who can rep out 25kg bench for 5 reps but if I was to
put it up to 28kg (assuming I only have 1.5kg plates) they can barely do 1 rep
with good form.
I then added 2x0.5kg to their bench next program and they were managing to rep out the 26kgx3 with ease. Add another 1kg next week and before u know it they are repping out the
28kg. As u can see they are a worthwhile investment if your just starting out and your gym does not have these.
So Before u laugh at the idea of using small fractional plates remember it might be stopping your progression and getting stronger faster.