If you keep in mind that, theoricaly, it takes (at least) three tablespoons of flax seeds to get one tablespoon of oil, and if you follow the Erasmus suggestion to take 1 tablespoon of oil for each 50 pounds of weight, you can understand easily that it is much more convenient to get EFA from oil than from seeds alone. I take two tablespoons of oil a day with four tablespoons of flaxmeal combined with sulphur-based protein (strained yogurt sweetened with stevia). I just cannot eat nine tablespoons of flaxseed meal a day. Furthermore, it is generaly not recommanded to take more than five tablespoons of flax seeds a day. Flax seed has a poisonous substance that can be harmful if you take more than five a day for a long period.
It is possible to grow your EFAs capital from food (fatty fish, nuts and seeds). I suppose that If you don't want to fall in a maniacomathematical diet, you could forget calculation and percentage, and merely add to your diet flax seed, maquerel, greens, sesame, sunflower, pumkin seeds and walnut, and you would probably achive acceptable result if in the same time you give up bad fat, and processed food. Artemis P. Simopoulos'book "The Omega Diet" (in contrast with the Budwig Oil-Protein Diet which is a therapeutical diet for people suffering of degenerative diseases) can help you to "restore the body's essential nutritional balance" on the basis of the diet of the Island of Crete. If you are interested, you can also consult Erasmus'pyamids (http://www.udoerasmus.com/pyramid/pyr_index.htm) the principles of wich I follow.
But, neither Simopoulos nor Erasmus will suggest you to ground your EFA taking on food only. The reason seems to be that we no more live in the Paleolithic paradise and that it is much more difficult to get w3 from modern food than in the old times. Both authors recommand strongly to use good oils and only good oils as a supplement to a EFA rich diet.