Here is a link to a blogpost I wrote on why I believe Counting Collections should be done weekly in all Primary classes. I also some information on Counting Collections in my Number Routines Presentation which can be found on the Ideas page.
The best place to learn more about Counting Collections is on the Tedd.org site. There are amazing video that show real classrooms using Counting Collections, as well as informational sheets. You will need to register with your email but they will not send you spam.