Good luck reaching your full potential as a distance runner if drills aren't part of your program. Vigil (and every other decent coach) has been preaching this for years -- and for good reason. Neuro-muscular fascilitation, Type II muscle fiber recruitment, improved running economy, increased athleticism and reduced chance of injury -- the list goes on. If every distance coach spent a year learning how sprinters train, distance running in this country would be in a much better place.
As far as when to do it, shoot for twice a week. In a marathon phase, you'd do drills and striders the day before your two hardest workouts of the week. If you're training for a shorter event and getting on the track on a regular basis, you can fold one (or both) sessions into your warm-up for track workouts. As in all things, you have to allow a period of time to adapt to the new workload.
For you non-professional runners out there who don't have an endless amount of time to devote to this kind of stuff, here's a sample session that I've had athletes do twice a week all year round. Obviously this is just an example. I'll also preface this by saying that a great source of information for this kind of stuff can be found at:
www.coachjayjohnson.com
-- which is a fantastic site.
Following a 15-30 minute very easy jog, do the following:
1. 2x25m “A” Skips**
2. 2x25m “A” Skips for Height
3. 2x25m “B” skips**
4. 2x50m Fast Leg (“Step over knee and drive down”)
5. 2x50m Backward Skip w/ both arms across body
6. 2x25m Straight Leg Shuffle to Bound
7. 2x50m Backward Run (“heel to butt, then reach back”)
8. 2x50m Carioca w/ high knees (“Step over knee and drive down”)
9. 4x20m High Knees for Speed (emphasize quickness through full range of motion)
10. 4x20m Butt Kicks for Speed (emphasize quickness through full range of motion)
11. 4x10m Fast Feet
Followed by 4-10 striders (100-110m in length), building from 5K to 1600m race pace, preferably w/ @120m shuffle jog recovery between striders. (Minimum 45-second recovery between striders – or @120m shuffle jog recovery.)
Notes:
**Emphasize dorsoflex position of foot/ankle – “TOE-UP!”
• last three drills – High Knees, Butt Kicks, Fast Feet – should be done in 4x [1-1-1] sequence together
Full recovery between each exercise is key.