There is definitely a physical limit for all of us.
Some of us will be stronger than others due to genetics.
Some of us will thrive on certain exercises while maybe not on others.
I can crush leg extension, while most of you do better than me on leg curl.
But ultimately there is a physical limit to our strength.
We will always want you to work as hard as possible but after about 2 years of hard effort, your goal will become to hang on to your strength as you age.
Even if all your weights stay the same over the next 10 years.....that is still progress because anyone not strength training is losing strength.
Use it or lose it.