It is rather less linear and more dynamic than that. Put simply, yes, you can complete the course and find work wherever it might be available. You are not tied to any holding pool. Many airlines will stipulate minimum experience requirements for direct entry pilots. Unless they operate a cadet scheme of their own it is unlikely that many graduating pilots with only their training hours would satisfy those requirements. Those airlines that do operate cadet programmes will (in the majority of cases) affiliate to particular Flight Training Organisations.
CTC operates a number of programmes leading to the completion of the basic professional licence qualifications, as well as providing intermediate and in some cases part of the advanced training requirements for the transition into specific airlines cadet programmes. These courses follow a number of pathways although much of the training programme is common to all of them. For example the "Wings cadet" course applies selective criteria for the completion of the licence programme, as well as the Airline Qualification Course (AQC). Successful graduation leads into the primary selection pool for many of the "partner airlines" that draw from it, in accordance with their own current requirements as they exist from time to time.
CTC also offers a "Wings IPP" programme when a candidate either doesn't satisfy the "wings cadet" selection criteria, when it may not be available, or when they elect that particular route. This programme utilizes exactly the same training syllabus as the cadet programme, but the risk shifts more to the candidate proving their ability in order to be placed in the primary selection pool upon graduation. It also doesn't include some of the intermediate costs (AQC for example) that are an integrated part of the cadet programme.
Some airlines (For example British airways FPP, and some other airlines pre-selection programmes,) utilize the wings cadet programme with a conditional offer of employment at onset. Depending on the level of financial support as a part of the contract, these graduates may be financially bound to discharge their commitments before they would be able to seek alternative employment in the (probably unlikely) event that they should elect to. If the conditional offer of employment could not be fulfilled by the airline, then it is likely the graduate would be free to take up any other offer that might be available at that time, either through the "holding pool" or through the open market.
Quite a few graduates of these programmes do go on to fulfil their careers at other airlines as a result of the experience they have gained with their initial placements. Once you have reached that rung on the experience ladder then the open market is available to you.
The enormous hurdle that ab-initio pilots face, is in finding the opportunities to get the experience levels that many airlines demand. The airlines that are partners of CTC provide (from time to time, and absolutely as their own commercial requirements dictate,) just those opportunities. It is a very cold world for low hour pilots seeking those opportunities without specific integration. Airlines without cadet programmes usually source their F/O's from the experienced open market. Without that experience they are likely to tell you to come back when you do have it.