It depends on your fitness level and goals. But I'd say give your legs at least one day to completely rest per week. I wouldn't increase weekly mileage like crazy. They say no more than 10% but that's just the dumb rule of thumb everyone parrots (incl. me). It depends on too many parameters to be able to have a general rule. Just don't do anything nuts like going from 5 to 40 in a week.
On 5 to 6 running days per week, I'd have 2 quality workouts (short intervals, long intervals, tempo, hills), 1 long run, and the rest being easy days. It's usually a good idea to space out hard/quality workouts. 1 day hard, next day easy, etc. For specific workout exercises, intervals and repeats are gonna be series of runs over a given distance, for which you want to hold a given pace, with fixed amounts of rest time in between. The distance, pace, number of series, rest time, all depend on fitness level and what you want to accomplish/work on.
If you don't have tons of experience, I'd suggest something along the following lines,
- Speed day: 10min easy warm up, 10x200m, 200 jog to recovery inbetween repeats, 5min slow jog recovery, then 5x400m, 400m jog to recovery in between repeats, 10 min easy cooldown. If that's too much volume, scale number of repeats accordingly. Look up equivalency tables to figure out approrpiate pace (see here or there). Specify your current running time over a given distance (what you can do now, not what your target), and look-up repeat pace in the training tab. That's about 12Km distance for the session. Scale number of reps up or down depending on target weekly mileage. This shouldn't be more than 1/5th of weekly mileage (so this would be for a 60+Km/week person). It'll work your turnover, getting used to moving your legs quicker than target race pace, getting you more comfortable at slower speed.
- Resistance/running economy: 10min warmup, 2x1mile repeats, 2min jogging recovery inbetween, then 5min easy jogging, 20min threshold, 10min cooldown. Again, about 12K, scale as needed. This is a running economy workout.
I'd build up the length of your long run over the first 3 weeks, from 14, to 16, to 18K, roughly. Then scale it back down after that. Don't run much on the week beofre your race. Go out a cple of times, maybe 5K each, easy pace with some strides (progressive accelerations held for a few 10s of meters at top speed before slowdown, meant to get the blood flowing without tiring your muscles).
5 weeks isn't much time at all though, I wouldn't expect miracles. In any case, bets of luck and feel free to drop by the running thread for better tips from people better informed than me.
if this is all too much work, just go out 4 to 5 times a week, alternate one day trying hard and the next going super easy. Increase mileage progressively the first 3 weeks before cutting down on the last 2, glhf
Fest will, thank you for taking the time to make this reply. I'll take your advice. Looking forward to smashing tough mudder and posting some pics here