Is this normal? -> Burning cleaning tapes every month

After we upgraded to BE 2012, we started burning more cleaning tapes than before. Around every 25-30days. I noticed that invetory job that runs everyday also performs cleaning. previosly in BE2010, we had a separate job to perform bi-weekly cleaning and it simply worked well.

1) How often does a drive needs to be cleaned?

2) Does the inventory job really runs drive cleaning as well? Can this be changed?

Thanks for any input.