Literature on 6 Days vs 7 Days when doubling?
M 37, I'm trying to decide if it's worth adding a 7th short day or adding doubles on my easy days. For context, I run 6 days right now, about 60-65mins on my easy days 3x a week, 65-70mins on my workout days 2x a week, and about +105mins on my long run day. I'm looking to increase my volume a little bit, but I don't know if there is any research about the level or rate of adaptation by going to 7 days vs adding in doubles, but taking a full day rest. My goal would be to start with one double of 30mins on one easy day and then slowly build up until I'm at doubles on all my easy days. I know this would be more volume over one additional day or running, but I'm not sure if there is any research that shows going 7 days in a row has some additional benefit.
I have 3 young kids, so I do like having one day off on the weekends to just hang out with them. It also allows me to schedule around any early morning soccer games they might have. On the flip side, adding in a 30min run for one day would not be too difficult to accommodate.
Looking for any literature that indicates what might be better from a training perspective to help make a decision on this.