Hi there i am doing bench press.I would like to know this. If someone does a lot of this workout with low weights but he does 1 set of 40 after 2 of 30 and 3 of 30 and 1 of 25.Does this part of chest become bigger?
Its a great way to build muscle, muscles don't know how much weight they are pushing, they only know they are being forced agaisn't resistance which is enought to grow muscles as long as there is progress. Progress can be made by increasing frequency, weight, repetitions, sets, speed, time under tension or by decreasing rest between sets.
Growth requires muscles to be fatiqued and broken down which can be done with light and heavy weights.
Nervous system strength requires heavy weight.
If you don't care about getting stronger its fine, why would you care after all... it bring no functionality in real life to bench press 3 times your weight. Or are you a mechanic who plans on bench pressing cars to change their oil?