i'm currently training martial arts 5 days a week, 3 for jujitsu and 2 for karate/thai boxing (one class). My current goals are improving maximal strength and endurance. Should i just focus on maximal strength on weight training days (aprox 3-4 days) or continue to focus on both maximal strength and endurance on weight training days?
Do two days of endurance and 2 days of maximal strength. The endurance is more important for you. See my article here at t-mag on HOC for a great program for fighters. I have had dozens of fighters tell me that the HOC program got them in better shape then anything that they tried before.
I would not worry to much about endurance training as you are getting plenty of that during your 5 day a week martial arts training.
I would go with the Strength training. Do this by hitting the "grappling" muscles one day and the "striking" muscles on the second day. I would not do any more than two days per week weight training with your schedule.
By "grappling" muscles I mean the three most important muscles that a grappler can have: Neck and traps, Biceps, Hips. Okay, that was four but I was originally counting neck and traps together as that is how I trained them when I grappled.
Striking muscles would be the following: Triceps and Quads.
I would stick to 6 to 8 reps and go for some size and strength. Occasionally dropping it to 3 or 4 reps per set.
Good luck, I admire what you are doing.