I wouldn't say I ever get bored of diapers so much as I would say that other interests need tending, and sometimes eclipse the desire to wear diapers. That said, it's been almost 20 years since the last time I experienced anything remotely like a "purge", and that happened during the first few months of my freshman year of college. My whole life was suddenly completely different, and all of the amazing new experiences were utterly distracting. It wasn't that I'd become disgusted with or bored of diapers. Rather, I didn't even think about them. The desires returned soon enough, however, and since then I think the only times I've gone a week or longer without wearing diapers have been times when I've been physically separated from my diaper stash--traveling, etc.
Having been married for more than 16 years to a non-participating spouse has also surely been a moderating factor--not so unlike living with parents, at least as far as diapers are concerned. So I guess I've also never been in a situation where I could go 24x7 for long periods or do other things that might lead to "diaper burn-out."