Soap actors are actors. Unless they're A-list, actors don't get to pick their roles, they audition for anything they can and fit: TV shows, movies, indies, theater, commercials, etc. If you limit yourself, no agent will want to represent you. Agents make money when you book a job. This is a BUSINESS, it's not about the actor.
Anyway, to answer your question, while there isn't a specific amount, it takes about 7-10 years not just of training (from a top-quality acting school! In addition to workshops and such) but also of low-level experience (student and indie films and community theater, etc.), and landing plenty of leading roles and winning awards, as well as dancing and vocal lessons and other skills. All of this goes into your resume. In addition to that, it takes learning and understanding the business side.
No legit agent will even consider taking you on as a client without a strong resume. And without an agent, you can't go to auditions for professional work, they are not open to the general public. If and when you get an agent, they would have to have great connections in the industry so that casting directors approach them when they cast for specific roles, for specific projects. So then, the agent goes over their client database and submits the clients that may fit those roles. Out of those, the casting director will invite to audition only a handful. The handful will take several rounds, each time a handful of the handful will get a callback, till the production narrows down the casting options. Out of hundreds or thousands, 1 will win the role (or a different one they didn't audition for). These are all highly-experienced and highly-trained talented actors. The competition is that fierce.
On average, an actor will win 1 role every 100 auditions they're *invited to*. Those 1 roles will mostly be small ones, on minor productions, including things no one's ever heard of. For higher chances of getting cast to a national TV show, like a soap opera, one needs not only the right looks, but also plenty of *professional* experience. So, in theory, it could even take 30 years to get that kind of role. However, for 99% of professional actors this will never happen at all. 99% of professional actors don't get more than a few days of work per years at best. In small roles, on small productions. You'd be lucky to get 1 good role, let alone a few.
Other than that, most actors continue training throughout their entire career. They always look to improve and learn new skills. So, basically, they never stop training.