Side note: My wife and I's investment career  will be ran on the side of our full time jobs as supplemental income on our road to financial freedom. 

 -  I periodically work temporary Project/Program Management gigs to supplement my income. 

Or, to supplement other investments. 

I have all of my bills on automatic payments, including HOA, supplemental taxes and mortgages that are impounded with taxes and insurance,  so unless I'm paying a handyman or an odd expense, I don't spend that much time managing my properties or paying bills. 

I have seen many a folk run a very small Property Management business on the side to supplement a low sales commission business.

What would be supplemental if we could see the migration of these colors since the last 5 years, or even since pandemic?

Many investors have been able to use 1031s to position themselves into passive investment real estate that pays throughout their lifetimes and uses the deferred tax to supplement that income.  

What I see though is that they will often supplement it with other forms of marketing like SEO, texting, mailing, RVMs etc so they are not reliant on just one source.

I kept adding supplements to the contract dealing with the giant Texas freeze the other week.

I am a GC and I use xactimate for my supplements and figuring remodels and re builds.