Not surprising, given how much you have been doing. If you can find your way to a couple of days off you will be pleased and surprised by how spunky you are on your return.
I am also thinking about doing something faster soon, either an assault on my very soft 2K time, or on my moderately soft 5K time. So far I am not too enthusiastic about longer pieces yet.
You were very prophetic in this post yesterday morning. That 7:56 2k piece you put up a couple hours after you wrote this certainly made good on your thinking...especially for a certain young stud trying to give 'old dad' training tips! :-)
My rational for rowing EVERY day is only to maintain fitness. While competing to set fast times is motivational, my primary goal is just to do something active every day. I don't think 40-60 minutes of exercise with an elevated heart rate, no matter how far off from a PR, is overdoing it.
I get a lot of motivation from reading your log. And other old guys, such as bl, PG, walk, dwildfogel, etc. I admire you all. But you each seem to have a slightly different approach to staying in shape...and unique philosophies about how to handle getting older. Me too. As one guy posted a couple of days ago:
...there is also the clear movement into another phase of life, one much closer to the end than the beginning, and it is hard to call that anything but a down. Not that one doesn't still try to make the best of it....
I think Charlie puts it very well - even world class athletes have written that on recovery/rest days/periods they will take long walks, easy bike rides etc. Recovery is just as important as training...ESP as we get older (I say 'we' because I am rapidly closing in on the elite group of athletes you mention).
Its not going to hurt your fitness not to do 20 minutes of rowing for one day out of ten or twenty or thirty, in fact it will probably help it...and you will quite likely feel stronger and more likely to pr, in one of the days following the 'rest'. Why not give it a try and see what happens?
"Rhea (2003) concluded that for untrained individuals and trained individuals a frequency of 3 and 2 days, respectively, per week per muscle group is optimal, which translates to 1-2 days rest between sessions....Ground based movements such as the deadlift, squat, and overhead press require more rest than smaller muscle groups such biceps, triceps, and forearm flexors."
I remember a couple of years ago when we were doing the challenge to row 5K every day in March, and I remember that my times gradually got slower and slower the last week. You can certainly adapt to rowing 5K a day, especially if you don't hammer it, and it will be good for you, but if your objective is to do some faster times, then some sort of interval training and adequate rest would seem to be necessary.