I dont see too many bucherim come around during the yr. it is mainly Purim, I think its very nice for boys to get involved in their yeshivos. After all there is a certain amount of thanks one owes to their place of learning.
As far as collecting for Yeshivos, in general we mostly get letters in the mail. We get lots of collecters by the door, I usually dont even know what they are going around for, they show a paper in hebrew which i usually cant read…we just usually give a certain set amount when pple come to our door.