The smartest thing would have been taking time off, as has been suggested by Bernie Leadon and Don Felder, and probably some of the others as well.

If they'd taken a year or even 2 off after HC, and taken some time for themselves, re-energized, and worked on songs at their own pace, I think we'd have had the Eagles for all those lost years, plus the best of their solo work, which would have inevitably came out of them eventually, possibly even better with the other band members input.

Wrap the HC tour, go your own way for a 1 yr period. Write with whoever you needed to, do whatever you needed to do, but be ready to go when that year was up.

You do that again after the LR album, and so forth...