Yes.
AT efforts (eg 2x20min) level me later in the day and I can feel it the following day if I've emptied the tank.
Heavy lifting (squats, dead lifts, etc) blows me out the next day and the day after that.
I can still recover OK from relatively short, max-effort intervals (I'm all Type II/fast twitch so this is my jam) even on successive days.

I'll plan workouts to account for fatigue and also quality.

I was trying to describe to odd situation where I hard a hard/big day... And 24 hrs later I perform surprisingly well...INSTEAD of being wiped out as I would have previously expected.

So, I'm trying to decide if I should begin to take some kind of advantage of this window... Maybe by planning two days in a row? Or...??

LOL, you kids are something else….when I was your age….

I’ve found that nutrition, recovery, and consistency, are the key to feeling good during a workout. To that end my Garmin watch surprisingly provides great information on my recovery and training readiness. Nutrition is a little bit trickier, especially now since I’m trying to get down to an aggressive race weight for next season (plus taking in more protein). Of all the things, for me when I forget extra protein, the next days workout is really flat.

thanks? But, I don't know how that helps with the question I'm asking. I'm not complaining about an inability to recover, nor was I asking for nutrition advise. If anything, quite the opposite, but in ways that are different than when I was younger.

What I'm asking about a delay in the onset of fatigue after a long/hard workout (2-3 hour long run, or a 90-120min interval session, etc) of 24-48 hours, such that I "could" complete a second workout of some type in that 24-ish hr window.

for example, my current schedule looks something like this (I'm a pure runner these days):

Mon: 6 mi easy
Tue: 12 mi with 8 miles of 5% grade hill repeats @ 10km pace
Wed: 6 mi easy
Thu: 12-14 mi sometimes with about 6 miles of 1-2 mile repeats (3x2mi or 6x1mi or 2x3mi @ 10km pace)
Fri: 6 mi easy
Sat: 15-20 mile easy
Sun: various (could be off, could be 2-4 mi recovery, could be 10-12 mi easy)

Normally, Sunday would be 100% off...its filler for the 100/100s...right now.

What I'm experiencing is that Wed/Fri/Sun I often feel much better than I expect to based on the workout the previous day. So, I'm wondering if there is some way to "stack" things to make use of that "next day window". Perhaps?

Mon: 6 mi easy
Tue: 12 mi with 8 miles of 5% grade hill repeats @ 10km pace
Wed: 10 mi easy (maybe with 2x3mi @ HM pace?)
Thu: 6 mi easy
Fri: 12 mi sometimes with about 6 miles of 1-2 mile repeats (3x2mi or 6x1mi or 2x3mi @ 10km pace)
Sat: 15-20 mile easy
Sun: various (could be off, could be 2-4 mi recovery)

I'm sure that would need some tweaking, I mostly just rearranged the first week above. Wed might need to just be all easy, or something.

I mean I guess I can just try it, and see. I was just curious if others had experienced similar...and, had already tried to make some use of it?

FWIW: I find Garmin metrics to be absolute SHIT. I mean honestly, it gives me recovery times of 4 days, and never things I should even do a workout (constant suggestion to rest). Just trash for me, worthless.

I think the Garmin suggestions are pure shit too. I always ignore it.
You're putting in a lot of miles and around 20% intensity. While this might work for younger athletes, older dudes just break down. You should back off the intensity miles and possibly add some elliptical or cycling to your aerobic volume cutting out some of the leg pounding mileage. Just my take.

Hi Tom - I have had those days also, but would still caution about “taking advantage “ of them. Past your 40s you could be doing damage if you pack to many hard efforts back to back. Regardless of how you feel you need to recover after a hard effort to make sure you don’t overload. A friend once told me after a marathon that if you don’t take time off to recover, you could be walking in the mall two weeks later and have your leg give out and wonder where that came from.

As I've gotten older (55), I've noticed the the first day after a hard day is surprisingly good? Two days after can be in the crapper, that's expected. But, I've had numerous experiences in the last 6 months where the first day after, I'm not as flat as I expected to be. For example....

Saturday, I ran my longest run in over a month (15 miles) at a solid pace. Yesterday, I expected to feel pretty flat. I woke up, and was indeed a bit sore. And the first couple of minutes into my run were a bit rough. However I quickly loosened up and was feeling quite peppy. I felt good enough to pop off a few unplanned harder efforts at 5km pace.

Does anyone else experience this?

When I was younger I would have been more likely to be very flat. Maybe I ran harder back Then? Dunno it seems odd.... I was pretty hammered when I finished the long run.

If I'm not alone, has anyone come up with a good way to take advantage of this window?

Im not sure that aligns with what I was trying to describe. I was trying to describe to odd situation where I hard a hard/big day... And 24 hrs later I perform surprisingly well...INSTEAD of being wiped out as I would have previously expected.

So, I'm trying to decide if I should begin to take some kind of advantage of this window... Maybe by planning two days in a row? Or...??