I did a 20 mile run last Saturday, and did a 22 mile run yesterday, so six day rest. Its not easy and it can take its toll. You have one eye on the marathon though, but i also know i have to learn to rest as well. Its a hard discipline to stop overdoing it, but you need to look after your body.
I have never stuck to a Marathon training fixed plan. I just do a very long run at a relaxed pace, and two shorter ones, in an average week, then stretch on off days. We are all different, and you have to learn a lot of it by trial and error.
When i first started running about 4 years ago, it was a Baptism of Fire. You learn from your mistakes quickly, like wearing the right shoes rather than your day trainers, and when to eat / not to eat before a run etc. There is a 101 things you can do to improve your running, and we all have our individual ways. Being a marathon runner now, I am still making little corrections. Be it to wear certain shorts which will hold gells better, or to use sudocream for chafing.
My question to all you seasoned runners then, are you still finding that running is a learning process no matter how long you have been out there?