I once worked at a company where I was the primary web dev on a small development team for an internal tool. The workload was very, very low and the pay was above average for my area.

I enjoyed having nothing to do for about 5-6 months. After that, it started to eat at me. I'd hop on reddit or HN only to find that all the links were blue because I had visited everything already. I also felt that my skills started to atrophy despite my efforts to write hobby projects or pick up new technologies.

I really struggled with what to do. The company paid well but I was worried that if I stayed like that for a few years, I would become rusty. I eventually left for a company where I'm now much busier but happier overall.

It is hard for me to say if I'd leave for the new job or not. However, I do know that I'd be using some of that free time to make sure I looking for a new job that wasn't a dead-end eventually. If not now, then perhaps something good will show up in a few months. I'd keep looking.