Do large number of attended conferences favour application to postdoctoral or tenured positions?
The purpose of attending conferences when you are at the PhD level and post-doc level is not for padding your CV, although people still want to see you have presented at some international recognized conferences. The main purpose is to advertise yourself and your research and to network for what could be your next position. In fact it is possible to walk out of a conference with some kind of contact or verbal agreement that sets you up for your future job.

For professorship application I don't think just attending conferences will help you, rather they will want to see that you have been keynote or plenary.