I occasionally I find them very usable. Before you ask on IRC (on a channel you haven't visited before) you will google it extensively. If the question is either a quick question that anyone in the know can answer directly with a yes/no like answer then IRC can be a good option.
But I especially find that IRC is better for very niche questions that won't benefit anyone else (and won't have been asked before) that also requires some back-and-forth debug style to get to the bottom of it.
Similar to problems where email doesn't work and you need make a call instead. A ten minute call can sometimes save you a week of emails if they are not quick enough to answer (common with large timezone differences).
Also much quicker, you either get the answer or you don't, either way both are good to know (so that you know to try something else).
But I especially find that IRC is better for very niche questions that won't benefit anyone else (and won't have been asked before) that also requires some back-and-forth debug style to get to the bottom of it.
Similar to problems where email doesn't work and you need make a call instead. A ten minute call can sometimes save you a week of emails if they are not quick enough to answer (common with large timezone differences).
Also much quicker, you either get the answer or you don't, either way both are good to know (so that you know to try something else).