Well, outline is important but non inclusion of outline may not cause your failure if you have written a good essay. So, if someone has missed to mention outline, we can’t say that he will not score passing marks. Outline serves both the purposes 1) It is skeleton of your essay, gives first impression and roadmap to the reader. 2) It is brain storming tool, and driving force for yourself.
Initially outline was not mandatory in essay paper, it was not asked expressly by the paper setter. From 2009 and onwards, outline has been made mandatory part of essay because it is explicitly demanded by the examiner in paper. So, it is better for us not to skip outline and encash few more marks by starting our essay with nicely articulated outline.

In order to avoid ill organized and poor outline, it is always advisable to work out a rough outline at the last pages of your answer sheet, revisit it and re- arrange it in proper sequence. If you are still not satisfied with that outline then start writing your essay with the help of that rough outline by leaving first two pages blank. When you are done with your essay writing then spare some time for the final refined outline, have a bird's eye view of your written essay and match it with the rough outline written at the last pages. Come up with final refined outline and write it on the first two blank pages. In this way you can produce an outline wich is in unison with the written essay material.

Regards

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"Jiyo to istarh ky log tum sy milny ko tarsy; maro to istrah k log tumharee mot par royain"