I've not seen it with LO, only after several years of the Carbonate at standard, old-school doses (~500mg/d). After a few years, about half the users are likely to be effected to some degree (goiter.) It's not unreasonable to consider that the other half are really just sub-clinical at that point, and may still be destined for sequela. Now the LO appears more efficacious, thus lower dose requirements correspond to reduced toxicity risk, but the biological effect of Li is still the same. Know what I mean?
For some people, it obviously suits their chemistry. For those individuals, daily LO may complement their over-all redox health. The woman I referenced before benefited from 180mg nightly, and 360mg for several consecutive nights when having an agitated episode (then returning to 180 once she had "stabilized".) Nevertheless, it's all about personal chemistry. I'm borderline hypokalemic about half the time it seems, so it's just not a good fit for me as a daily supp. I find it best to avoid things unless the benefit can clearly justify the sides, and these damn muscle cramps have gotten ridiculous as of late!