First time I've seen this 5:1 ratio. When I get the chance I will check my ratios. But mine is a marathon plan so I expect something more balanced.
Should you do a run focused training block
Surprise surprise. My average ration of bike miles to run miles is 5:1! Slight variation from week to week, highest is 7, lowest is 4. For some weeks my plan does not have run distance estimate because I am scheduled for a time based time trial. Even then, those are recovery weeks so the distance will not be huge.