I rarely use it unless I'm starting a new (old) series where the many earlier chapters are difficult to get.
If I just keep an eye on TT + the various scanlators sites, picking up the 1 weekly chapter of every series can be done while sitting around on 4chan.
I even read a few series which are only released onto IRC, and they're still uploaded elsewhere. It's just less hassle if I can do everything with my browser.
For grabbing a couple hundred chapters of an old series though, IRC is unparalleled.