Regarding pipeline management - in which situations you consider an opportunity must be closed as "Lost" and in which should be acceptable that sales team "cancel" it? I mean for example if a customer gives up on a project, and no bid will occur, it is acceptable to cancel, do you agree?
Personally I would say an opportunity should never be "cancelled".
Let me elaborate further.
Let's just say that stage 1 in your opportunity pipeline is "Identifying/Qualifying" this is where you are (as the name suggests) exploring the opportunity, and qualifying if a genuine opportunity exists. At this stage and only at this stage a sales rep can, in your words, "cancel" the opportunity, and change the Opportunity Stage, but I would call it something like "Dead/No Opportunity" this stage means that this account doesn't have an opportunity AND NEVER WILL. If the prospect won't be buying now, but may do in the future, then that is not when "Dead/No Opportunity" should be used, because you will want to capture why the prospect is not buying now.
Assuming the sales rep does not change the stage to "Dead/No Opportunity" then the opportunity's stage should be set to your "real" stage 1, something like "1. Discovery". Once an opportunity moves to "1. Discovery" it can never be "Cancelled" or set to "Dead/No Opportunity" only "Closed/Lost" if needed, why? Because if your sales rep has identified that the account is valid, the prospect is the kind of company that you work with, and there is a potential opportunity there, then if the opportunity dies, there is ALWAYS a reason why, and you would want to capture that reason.
If you find that there is a frequent need to "cancel" opportunities, then I would focus on establishing when an opportunity should be created in the first place.
