2003 ran a web hosting company along with a few other websites. Got an offer for 1k on a $8 domain sold it and that sale made me go full throttle in acquisition mode as I'm like $992 profit for no work sign me up. So back then I would say full time work which included web hosting, various websites, domaining etc... so a diversified income stream with full time work. Full time work was due to excitement of let's try this, let's try that etc... excitement I suppose of being something new, some winners and some losers.
Over the last 15 years some sites still exist, some I've gotten rid of and some new ones have appeared. So same strategy as back then today=diversification just work load has shifted from full time work into part time work as over 15 years ya waste $/learn/adjust a few things. I've never done outbound and I don't sell any domains under 4-5 figures so not much work has really ever been involved on the domain end. All my domains are on sales pages and in the process of working on my websites I just respond to domain offers at the end of the day. I shoot my price/negotiate and if it sells it sells if not the recurring revenue stream I've created over 15 years really makes me not care as I don't really need the money and holding costs are only $8 year so I've held for the 1k, 6.5k, 7.5k, 16k etc... sales off of $8 purchases. Domain value is determined by the quality of the domain and having the "right" buyer on the line. Patience is needed for maximum return value. Not needing the income helps with that. I've rarely parked domains even when it paid better as my focus was always sales first and I've always had enough of my own developed websites where I'd rather link my own websites from my sales pages than sell that traffic off to google. I like to keep things in house or full circle continuing to increase the recurring revenue each year.
Diversification is key to online strategy, investments etc... One sector could drop cold and it wouldn't even phase me as other sectors continue on. Domaining should be a piece of the internet pie not the whole pie.