If I were you I would not change the balance between resting and running workouts.
You are breaking the balance between resting days and running days and so, your body will not get adapted as expected...
I mean, nothing happens if one day you feel bad, tired or sick, skip that training and forget about it. But, if you systematically change the plan, that, for sure, is going to affect your performance at the target day...believe me...
The resting days are placed on those days in order to ensure that your body get the desired adaption. If you rest so much, your body will "relax" and so, the next training day will be as starting again almost from zero...
By the contrary, if you don't rest (3 days on row running and one of them longer) , your body will be so fatigued and so also, your body will not react positively and, often, it will lead to getting injure...
No matter the pace or the target time...
I have experience preparing runners for marathon and, believe me that following the training plan is a must
You have to get sticked to the plan.