I found this handbook for C & W supervisors on Slideshare ( Dating from 2011) Pages 24-30 have the maintenance schedules you requested. The tables in pages 29 and 30 describe the maintenance to be carried out at primary and secondary depots based on the total distance covered by the rake before returning to the primary Depot. It's quite informative, please do go through it.
click here
It is recommended that the coaches be maintained after every trip. Even for trains which have RSA with 3-4 trains, maintenance is carried out regularly at...
more...

the terminals. At the most, only the External cleaning is done once in a week at the primary base and other usual routines are done regularly at the secondary base or other terminals. For trains with total run length (to and fro) 3500 KM, complete maintenance is done at both terminals and for run length less than 3500km, other than External cleaning and brake system maintenance all other maintenance is done at both ends.
For example, for Seshadri express, interior cleaning and other passenger amenities are to be checked at NCJ and SBC. Brake system is checked before departure at both NCJ and SBC. Only the external cleaning is carried out once in 4 days at CCT. All other checks and maintenance are carried out everyday after it reaches the terminal (NCJ or SBC). Even for Gautami and other daily ONT's maintenance should be done after every trip. At the most, external cleaning can be skipped but not the others.

Oh, I understand your concern. I am also from Kakinada and have wondered on more than one occasion why Gautami occupies 1 pit line for the entire day. From what I've gathered, it usually takes around 5-7hrs for a proper maintenance for one rake. ( That's why Bhavnagar express is usually delayed in the morning when Shirdi Express is delayed the previous night) and Gautami being a high priority ONT and also the only 24 coacher from the depot, extra care is taken. (The same is the case with the other important ONTs in the state. They are all high priority trains and run full through out the year.)
There is still room for a few...
more...

more weekly trains from COA with the current facilities and maintenance schedules. I think if any more new trains materialize, then C&W will be definitely forced to work on a more efficient schedule.