I thought only the really, really serious ones would last forever. :(

Well, that would be an extremely rare case. You won't be winning (losing) that lottery!
If your anal canal is super tight or even very tight, then reconsider stopping the cream, every little bit of loosening helps. And it can make the difference.
Diltiazem being a BP cream, can be used long-term like other, oral, BP meds. Just make sure your GP stays aware of your use.

I had to use the cream for 4 months before it healed. I think healing from the AF has to be a priority or it can turn into a chronic condition which usually does need more intervention.

It is hard to regulate the bowels but eating a high fiber cereal like All Bran Buds every day and getting probiotics and fish or flax seed oil can help make you more regular with fewer potty surprises.

Oh, no! I wasn't thinking of actually stopping the cream yet. I was just wondering, in general, if there's a point where you can safely assume you're screwed (the cream isn't going to work). XD

I'd probably throw in the towel after 6 months.

I think if it has lasted for months and months and the cream is helping, but its still not actually totally gone away, then you should consider more intervention.If it develops scar tissue through being left, then it will take even longer to heal, even after LIS etc, so its probably wiser to seek a good CRS!!

I agree with Lecia and Val, that is a very honest answer !
I used the cream for a year and felt almost healed, then i came off the cream and reverted back to square one :(

I was once advised not to wait more than a year. It is all up to you and your level of comfort and pain. Some people heal with creams, some heal after 2 years like Happy, some have LIS and heal in couple of weeks, some have LIS heal and get fissure again - some have 2 LIS surgeries and still have problems - there is really no rule , in my opinion : (. The only real direction is what statistics say - and that is that most people heal over time - this or that way - small
precent never : (.
All the best !!!