Burnout can equally occur if one is not busy enough and does not feel useful.
Ive been in both situations. Ive done the consultancy thing and although I learned more there than any other job since, it was always a baptism of fire, jump in, paid by the hour so expected to know everything, if you dont, work late until you figure it out. I couldn't keep that up long term, perhaps thats just a reflection of my personality.
Ive had other jobs since where the workload is pretty light in comparison. Not too many databases, schedules are not so tight, and days are easy. Life is prioritized over work in a big way, which is a massive plus. Its great for a time but after a while I felt like I wasn't contributing enough. I've been back to my managers a number of times to get more responsibilities allocated and often i was given stuff just to "keep me busy" as it was put.
I burnt out big time late last year in this role too, I felt i was only doing busy work to keep me from being idle but not work of real value. This was worse than being too busy and overworked. I was anxious all the time, i was not sleeping, i was not eating, my health suffered. I was not present when at home so my family suffered.