extra week?

does anyone else build an extra week into their training plans to make up for screw-ups that might occur? I'm putting together my training plans, and I'm contemplating putting in an extra week, because I KNOW I probably won't get all the miles i'm supposed to get in the week of spring break, and rather than totally stress out about it I'd rather just have a built in week where I can relax my milage a little bit. there's nothing wrong with this, right?

As of right now, I'm planning on starting a plan next week for about 8 weeks that includes 2 days a week of speedwork, with some surges thrown into my long weekend runs. it's supposed to be a 6 day/week running, 1 day rest schedule, but I'm taking out one of the easy running days and putting in a cross training day (and keeping the rest day, of course). The long runs are only supposed to go up to 9 miles, so I won't be going crazy with milage or anything (I think it goes up to 32 mpw or something), i'll just be trying to gain some speed. Then I'm going to start an 'advanced' half marathon training plan where the long runs go up to 17 miles. I figured that should work just fine to train for the 25k (15.5 miles). That plan is 9 weeks long, I think.

I'm also going to start really tracking the milage on my shoes (I got a new pair for Christmas, so I won't have to shell out the cash when it's time to switch!), and making sure I take my glucosamine, since I 'forgot' to take it for the past few weeks and my knee gets cranky when I do that.

I'm so happy I can go back to hating OSU again. but way to go buckeyes, in helping make the Big Ten 2-1 today (because evidently Iowa, land of the most boring driving ever, lost). Woo Hoo!