The Importance of a Relieving Letter
A relieving letter is a formality, and in reality, your "experience and learning" on the job that you are about to leave is more important than the said letter per se. In the present-day world, a new employer will want to be certain that they are not taking on board a deserter, traitor, a dishonest employee, or an incompetent employee, and there is nothing wrong in such expectations. But a "relieving letter" or at least a "resignation acceptance" letter assures the new employer that you do not belong to the above-mentioned categories. It is therefore in your interests to not go into a frenzy and desert your present job carrying a "liability" of not being able to convince new employers of your credibility. Competence without credibility will yet be a problem now and in the future!
However, if you state the facts and the new employer accepts these, you could leave the present job successfully without getting your profile/prospects tarnished!
Follow the Custom for a Safe Transition
A safe approach will be to follow the custom and get relieved properly. If you wish to either take a chance or if you have to take a chance, the outcome will remain unpredictable with greater chances of things going against you than for you! Three months is not so long a period that you should risk your career for this deemed urgency. It is perhaps better to find ways and means to contain the urgency than to stake a career!
Your decision will depend on your situation, which only you know best. We can only wish you well!
Regards,
Samvedan
December 5, 2012