Lock my bicycle on busy or quiet places? When I lock my bicycle I try to lock it on quiet spots, usually on street racks situated on secondary streets.

I think it will be less visible so it  will attract less looks. On the other hand, if a thief wants to steal it, he will have more time to act before someone spots him.

Is it better to lock the bicycle in crowded or quiet locations?
It is all subjective, but I would say that a public place is better (as I have previously answered to a similar question). 

Most bike thefts are opportunistic; unless you've got an especially desirable bike the theft is not about your bike, it's about stealing any bike. So the key is to reducing the opportunity to steal your bike: 


as you point out, reducing the amount of time to work on the lock(s) 
make it less desirable and more identifiable (dirt, scuffs, mods) 
give alternatives - parking next to a shiny newer more expensive looking one with a poorer lock 


I would also say to try to use a public bike rack - then you've also got a chance that a fellow cyclist would interrupt or at least deter a thief. Several times I've seen someone suspicious loitering around a bike rack when locking/unlocking my bike and I've taken longer about it so as to make them feel uncomfortable and move on. I don't want my bike nicked and spending a few minutes to maybe slightly protect someone else's makes me feel like a good citizen.