How long can introductions last?

Hi everyone,
I'm just curious if anyone has any experience with very long introduction periods for cats? How long can it be necessary to keep them separated?

I've posted a couple of times with my introduction woes...I actually completely botched the first attempt at introduction and had to start over. (For the record we are introducing a new 4-year old spayed female to a 6-year old neutered male who has never lived with another cat his entire life.) After the failed first attempt, we isolated the two cats from each other completely for about 2 weeks. Then we began the reintroduction.

The lady we got the cat from had a friend who runs a cat rescue, and that friend uses an introduction method where the new cat is put in a dog crate (bigger and more open than a cat carrier) for an hour or so at a time and the other cats can come up and look/sniff/whatever. We are using that method (along with scent swapping and getting them to eat near each other), but the process is very slow. The cats get to see each other for about 1-2 hours day. The rest of the time our new cat lives in our spare bedroom. However, even after a month of this, our resident cat has never gotten any closer than 2-3 feet from the crate, and the new cat can completely intimidate him into running away even in though she is in the crate!

I guess I just wonder if this is going to work. I love our new kitty, but I learned during the first attempt at introduction that she is quite aggressive--and our resident cat is anything but. How long should I keep trying? How long might it take?

I see this was posted in april. Did they ever become friends? I hope so.

When I introduced our kitten to our 1 year old (both females), it took about 10 days. I didn't crate anyone or separate anyone. I just let them be. The little one got hissed at a lot, but on the 10th day the 1 year old just started running and tumbling with the 2 month old kitten and resumed sleeping on my bed. She made sure she got her spot though. They still have their days when the older one doesn't want to be bothered, but doesn't everyone!

It may take a while, my 9 year old, the only cat for 9 years, is still adjusting to my 2.5 year old stray. They are not buddy's for sure and they have their separate boundries.

At least, after one year, my 9 year old doesn't act aggressive towards the stray, but she does tell the stray what to do and she does use the stray's litter box. She is such a bully. She knows not to use the stray's litter box and she does it anyway.
And who knows what goes on while I am not home, I did spy once ( she thought I went out) and saw my 9 year old stalking the stray, you should have seen her face when I came in.

The stray is such a good kitty, I have no issues with her. I would keep your cats separated, give them separate litter boxes and such so they each have their own space and territory.

I tried every introducton method I could find, and I faced it, they are not going to be buddies--as long as there isn't any bloodshed they will be fine.

I guess my main worry is that this won't work at all. During the first (failed) introduction, the new cat (Tomoe) often tried to intimidate the resident (Honzo)--she would charge at him, run after him, attack him, everything. But he is consistently fearful and will not stand up for himself. Right now we have been exposing them to each other's presence (with the crate) for a month and I've barely seen any progress from Honzo. (I'm mostly worried about him because Tomoe doesn't seem fearful--I think she wants to pay with him.)

But I feel helpless because I don't know how to tell when they're ready for more interaction. And I don't know if Tomoe's aggression means this is never going to work...from what I've read it seems like aggression is the biggest deal-breaker in cat intros.