I'm going to give my opinion, as someone who was and still is impossible to replace. I inherited about $1M+ in 2010. Added that to my portfolio and could have squeaked into ER somewhat frugally then. By 2014 I had enough of being chronically overworked and burned out. I gave my notice, and a week before I was set to be done, there was an emergency situation at another hospital staffed by our group and I filled in (it was much easier and way more interesting). The group hired about 5-6 independent contracting physicians to do my job and also had a nurse practitioner fill in once a week (she still does this work). I was hired back on an hourly basis since they never hired anyone to do the job itself, but there were more and more holes in the schedule and I was nearly full time, with more pay but less benefits the last couple of months I worked in 2016. So I gave final notice last April and finished at the end of July. That nearly two year time frame of part time work, taking off and traveling when I wanted to, putting more time into my home and my own health, was a great transition period.
If you enjoy some of your work, but don't want to do so much of it, get out of the directorship, and cut back clinical hours. Depending on your specialty, you may still have long days, or maybe your days will be shorter. Certainly you should work fewer of them. You will continue to feel useful and valuable, and you will have increased time to remember how to live the rest of your life. Think and remember the things you enjoyed doing and think of the things you would like to start doing.
In general, 6 months notice should be enough time. However, there are physician shortages in many parts of the country, and just recruiting a good candidate may take a long period of time. So if you think 2 years notice is helpful, for your organization, then go ahead and do it. Once you have decided to cut back, give a long notice time, as long as you can. Medicine is not like working for a big corporation. They will not kick you out. They will keep trying to drag you back in!
When I first stopped working full time, it was abrupt. I felt rather sad for awhile. I kept thinking I should have had "x" kind of career, but instead I had "y" kind of career. But that quickly eased. But since I ended up continuing to do some work training others, and very part time, easing into ER was so much easier. You are wise to consider the part time path. And I would cut back to half time. Don't just cut to 0.8 FTE. I tried to cut back to 0.8 FTE in 2013, but since my days were 12 hours long, I worked 48 hours instead of 60 hours per week. It was still too much work.
From a fellow physician, 10+ years older than you: remember: time>money. You can't buy more time to live your life. You don't owe medicine any more time than you want to give it. There is no debt to society that you personally have to pay with your time and your life.
One other thing, see a good estate planning attorney regarding the inheritance. As a physician, you are more vulnerable than many to lawsuits, and you want to protect your estate and structure it in a way for asset protection and estate planning. It is money well worth spending.
