how long does it take to advance shoulder strength to 50kg with 3-5 rep training

Nobody could answer this, strength gains always come down to the individual. It could take weeks, months or years depending on yourself and the way you train and eat.

Why does it matter how long it takes to get to that weight?

 

Only thing that can be said for certain is that the sooner you start the sooner you will get there.

 

Good answer.:good:good Only thing I can add is to take it easy getting there and don't try to lift more than you are capable of. Causing an injury only serves to set you back weeks, at best, or months of lost time. Sad thing is, when you are hurt and can't lift, you can lose all what you've gained.

 

do you mean 50kg dumbbells or 50kg in total on the bar

and how heavy and how tall are you?

 

Like many of the answers you already got, it's such an individual thing from person to person. But here's an example from 2 of my nephews from different fathers.

Nephew 1 is now early 30's. At one time he worked out pretty hard, took Creatine and Whey Protein to gain size and weight. He did so over a years time and picked up his lift totals by about 50 % from where he began.

Nephew 2 is now in his late 20's. He's always been into lifting when playing football in high school and it continued to a lesser degree for several years and he stayed about the same. Within the past 4 years or so, he's taken it to a much higher level. He watches what he eats, takes supplements, works out 4-5 days a week for at least 1 to 1 1/2 hours each time. He works heavy and his progress has been insane. He's now lifting 100%+ over what he started doing when first getting back into the gym. His high bench press is now 450 lbs., He does squats on a machine in the 1000 lb. range. His curls are 150 lbs. on the preacher curl bench.

I've never asked him but in the back of my mind I'm thinking he may have done roids. I hope not because he's always been very concerned about his overall health and with all the info out there about the damage steroids cause, I'd hope he's staying clear of them. The thing that makes me think he's not into roids is he's calm and a very gentle guy and my experience with people on roids is they can be plum ****ing crazy at times with roid rage.

 

you may never get there, if you dedicated your traiing entirely to weight training i would say a couple years, MAYBE... 50kg db is very heavy for shoulder press. I dont know anyone who lifts that weight.
Mate if you can lift 30kg db i would class that person as strong.
If your main training is boxing, i seriously dont think you will get to 50kg db.
Not being negative just my honest opinion

I know guys who have been doing weights for 5-6 years and they cant lift 50kg db and i class them as strong guys.
but people have different strengths, never say never