How long does it take to train one to be a skilled worker?

Your question is an open question and needs to be specific to have the correct answer.

In such to be specific with the nature of the job or specialization that the worker needs to fit in.

In general you would follow the pyramid of the specialization and check on which level is that worker needs to be fitted, then at the level intended (as it varies from level to level) you should follow as a minimum the legislation (if it is a standardized job or skill) related to that level, then to follow the organizations specific requirements that needs to be fulfilled.

In general training a welder is different than training a mechanic and different than an electrician and so on for the base line.

Then its different than mid-management than senior management personnel and so on.

Hope that satisfies your query and good luck.

Well it is a really subjective question and it will vary from case to case. For example, if you are dealing with people in IT, it takes an average of6 months on the job training. Same way, for Sales and Marketing professionals, basing on the industry it takes an average1 week to3 months. In case of service industry it can take up to4 months time. It is based on idealistic situation. But again a lot will depend on the capabilities of the people involved.

Most times it depends on factors for instance, is the trainee very intelligent and smart, is the skill very complicated, is the method os training very effective?

if these answers are supplied the answer will be a lot simpler to probably deduce.

Training of people depends on the required field and the type of training required As each country determines the duration of the training program and its content and according to the approved jop description of the  countries, which are often from 4 semesters or 6 semesters are usually shared with the labor market.The continuous training associated with the needs of the labor market has its specificity, there are training programs from 3 hours up to 4 months sometimes depending on the requirements required by the labor market

First to assess the skills gap then set required training to achieve the goals. It is not fixed.

It depends the field of operation

From that we can determine the duration.

IT DEPEND ON AGE, QUALIFICATION,ASSIMILATION, AND MATURITY, ACTUALLY FOR ADULT AND MATURED CANDIDATE ,MUST HOT LESS THAN ONE YEAR WHILE OTHERS MAY BE MORE FOR BETTER UNDERSTANDING.