As I've said a few times, Lully is my obsession at present. I take ptr's point - maybe more seriously than it was meant! - that obsessions like this leave you sleepless & you also miss out on other music. It's unbalanced. Plus, when I had obsessions on other music, pop songs etc, I usually ended up a bit 'scunnered' with it after I'd moved on, & didn't listen to it again till years later when it had recovered its freshness.
But there's nothing like an obsession for making you explore the depth of a composer or style. It's like falling in love - you couldn't live at that level for years & years, but it does kickstart a relationship. I think obsessions must be hardwired into the human brain, as a learning tool.