Would like to know whether serious investors do up their own analysis from other ppl’s analyses or they really crunch the numbers (stock prices/balance sheet/global news) from scratch by themselves.?

It's actually a combination of both and it depends on the need as well as individual people's time.

Successful investing is actually 90% asset allocation (the rest being management, fees, skill etc). Not to be confused with trading, where you get the best forex and options traders (looking at you Jon) putting up some ballistic annualized returns, so its hard to tell when you ask 'serious' investors what they do specifically.

I have a pretty decent record for investing, but my timing was certainly fortunate (the bulk of my investing was done at the end of 2016 and onwards), so you have to determine who your role models are in this field before you consider their analyses as part of your 'portfolio' in the future.

I'm the same as Luke. I do some of both, mainly because doing from scratch requires a lot of time. I'll look at the numbers done up by others and do my own analysis and decisions from there!