As a teacher myself I use all sorts of things to reward and recognise children's behaviour, effort, achievement. Stickers are just one of those things so it wouldn't be possible to state that any one of them in isolation was the cause of improved/otherwise behaviour.
The idea behind stickers is of operant conditioning - if a reward is given it will increase the frequency of a behaviour. In schools the long-term aim/hope is that eventually a child will want to engage in a particular behaviour because it is intrinsically rewarding to them but the stickers/whatever are a stepping stone on the path to that goal. If you do a search for work on ABA you may find some useful information about the use of rewards in learning.
Personally I find that all children (I'm talking aged 4-11) respond when they have been recognised and I would far rather my classroom was a happy place where children were rewarded for the 'right' thing, than a place where I spent all my time highlighting what they shouldn't do. In my classroom children can earn raffle tickets for all sorts of things be that being polite/kind, sweeping up without being asked, waiting patiently, reminding me about something etc. etc. These go into a box and, at the end of the week, two are drawn and those children get to choose a prize (gel pen, rubber, sparkly pencil etc). The raffle ticket itself is a tangible reward but offers greater (kind of!) possibilites. I also give out team stars related to co-operative working (winning team get to choose a prize from the box too) and sometimes I give stickers. The stickers I give say, "ask me why I'm wearing this sticker" and I am always very clear about the reasons for giving a sticker. The feedback from the children (via anecdotal reports and also school council) is that all these systems are appreciated and all the more so when they are implemented consistently across the school as was the case in my previous school where we made it part of the good behaviour policy.
It's important to remember that the majority of children in a class do work hard and behave themselves yet it can be easy to overlook them and over-reward the child who struggles to behave. If a teacher makes a point of rewarding those who consistently do the right thing it will send a message to those who don't that that is what is needed in order to be rewarded (read up on DRO - direct reinforcement of other behaviours), it is often more powerful for a child to see the correct behaviour in another child than it is to be told by an adult what to do e.g. "X, that's a raffle ticket for lining up so sensibly".
Oh, and I make it very clear that anyone who asks for a reward doesn't need it... I do however sometimes give them out (usually raffle tickets) if another child, not the best friend, comes and tells me about something brilliant another has done - children are surprisingly good at encouraging each other towards rewards, especially if it's someone who needs it more than others.
I dislike 'golden time' because children who need incentives to behave need something rather more immediate and those who behave anyway don't really gain anything by having golden time once a week if it's timetabled anyway. Tickcharts, stars, raffle tickets, stickers - all work some times for some children but they need to be used with thought and as part of something bigger.
I may not have explained myself very clearly but I do think that a well-designed and thoughtful consquences (both positive and negative) system can work wonders in classrooms but they must be linked and logical.