NOC for government employees

Sir, I am working in a government job, according to which regular employees can seek NOC for outside employment only 4 times in a year in line with DOPT guidelines. I have certain queries regarding this rule: I tried to read about some DOPT norms and according to my knowledge, there is a limit of four only in case of forwarding of applications through propel channel. Does this even apply for advertisements, wherein a candidate can apply directly and NOC needs to be produced at interview stage only? Is there a limit to which number of times a central govenment/PSU employee can sit for job exams? When should a candidate inform the organisation about sitting for a recruitment exam if only NOC is required at interview stage according to notification? For getting a NOC, should an employee seek permission for sitting in the exam first or can apply for NOC just before interview stage as this would ensure a candidate wouldn't just exhaust the limit of 4 applications in vain? According to my colleagues, my office has refused NOC in the past on the ground that the employee didn't inform about appearing for the exam even though he was on casual leave on the date of the exam. Is it necessary to fill all your work experience details in an application form for another job? Does this apply for PSU experience too? There are certain advertisements to which i applied even before joining this job whose exams/interviews are yet to be conducted, should i inform my office on appearing in such exams? Would i require a NOC in this case? What if i exhaust my four chances and in service, i apply for a better job without informing them of my current job and luckily get selected and then resign from my current job and join the next job without producing any NOC, will i have done anything wrong? Lastly, can anyone shed light on why there is a limit of 4 when to aspire for a better job and life without compromising on my current office duties is a basic human right? I know the list of questions is long but this is my first job and i just want to understand the rules regarding another job application.