Hi.
From freelancing and business point of view which will be the winner? If I do many small projects? or if I do little but big projects? For example let’s say I will have maybe 6 small projects in a month and 2-3 big projects every 2-5 months.
Which will bring me more money?
Far too many variables to give that a proper answer!
6 jobs per month @ $2000 assuming that all the jobs are the same, it could be 6 jobs @ $150
or you could get 1 job @$10,000 which takes you 3 months - which is better? who knows? could you get those jobs? who knows?
Too many variables 
It really depends on your situation. My situation is that I am a freelance PHP web developer. I often do work sub contracted from web development/design firms or sub-sub contracted (so 1 to 2 layers away from the client). From my experience I would have to say that small to medium (hours to week long) projects are better. You can charge a standard fee for common tasks you do often and they will take you less time than you charge. With bigger projects and a one-man band it is too easy for something to go wrong in my situation. When you’re so far down the pipeline just try charging for those scope creep items 
lol, it’s a battle!
A mix is best.
Some smaller projects for security and stable income and few big ones that can take longer but have higher returns.