Please Help: How Many Questions On A LIKERT Scale Questionnaire

I'm currently pursuing my Master's degree, focusing on Learning Transfer. My research instrument will be a Likert scale questionnaire.

My questions are:
1) How many questions or statements should I include for it to be on par and for the information to be reliable, valid, and generalizable? Should it be 20, 50, or 100?
2) Are there any samples of questionnaires on Learning Transfer available that I can use as guides?

Your support is appreciated.

I think I oversimplified my comments. I'm busy with my MBA and currently developing a Likert scale questionnaire as the instrument to collect data. The main emphasis of my research focuses on "Barriers to Learning Transfer." My question, therefore, relates to the length of the questionnaire. I'm using 6 scales instead of 5, basically to avoid the tendency of selecting the midpoint e.g., 1, 2, (3), 4, 5. Will a questionnaire be sufficient with 20 or 30 well-constructed questions or statements?

I assumed you were a student. You have not addressed all of my inquiries. Have you read and comprehended the material from the link I shared?

Yes, I'm a student and far from being an expert. I'm currently still reading it and need to do it one more time to fully grasp all.

Basically, the aim is to investigate the perceptions trainees have regarding supervisor support before, during, and after training, how this support contributes to the achievement of the transfer of learning, and also the indirect contribution of this supervisor support on other variables, e.g., motivation to learn, etc. Broad and Newstrom identified this support as one of the facilitators to the transfer process.

Other than the perception of trainees, what constitutes supervisor support, etc.?

The objective can thus be: Investigating the variables that constitute theories of learning transfer and synthesizing them into a typical common understanding that depicts the most effective methodology for the transfer of learning within organizations.

So! From a lay perspective, I need to construct a Likert scale with 6 scales from "Strongly Agree" to "Strongly Disagree" to try and get to the bottom of these perceptions and realities regarding supervisor support for training. Hence, I wanted to know in terms of the number of questions/statements that will be more or less exhaustive of the topic and at the same time not be too long for the respondent to lose interest. Samples on the topic, if any, will be dearly appreciated.

Dear Sir,

I have read the document and must admit that it is quite informative and very useful. It will surely come in handy.