How long do you give a Roo to do his job?

I have a Buff Chantie roo in with some hens, he has been in there for a month and a half. I have set 2 batches of eggs and out of 3 dozen i only have 1 fertile egg. I just put another batch in the bator today so i will see in about 5 days how it goes.
Do you think i have given him enough time and should pull him out and put in a different roo or should i give him another couple weeks...What would you do

I left my inadequate roo in all summer last year, only because I didnt have a replacement, and he never did get the job done, so to speak.
I think he had gone infertile, because I have a new rooster and the eggs are looking good from some of the same hens.
I would say take him out, put in a new rooster, and if you like this guy better try him again in a couple weeks, maybe the alone time will get him to perform?

Whats the weather like over there? roos dont really start getting going until the days get longer and they get some warmth on their backs

If you are able to then remove him and feed him up on some high protein food, chick crumb if you have it or tuna (rinse off any brine) or cat food are also good, if you are able to extend his days by keeping him in a shed with a light on 16 hours a day then all the better.

Then put him back in with the girls after 10 days or so and he should work his magic

I expect to start getting fertile eggs within a week of adding the cockerel once the days start to get warmer

If you still have no luck then it could be that he is having treading difficulties so you could also try trimming the feathers around the birds vents so they are more able to make contact, this would be more necessary with big fluffy birds such as Orpingtons though