On some occasion we would rent to them and even fewer we would have to evict. 

I have witnessed racial bias first hand on several occasions.

On rare occasions I've been willing to stretch it to six months.If your tenant wants to stretch it out more than six months, I would tell her to go apply for a personal loan at the bank, pay you in full, and then she can make monthly payments on her bank loan.

Is there any occasion you regretted not hiring professionals for a specific task/service?

With long term leases you hopefully only have to interact with your tenants on rare occasions however that can be significantly more burdensome with AirBNB.

Banks and lenders like to make things over complicated "on occasion".

At the Class B-/C property, we experience a higher level of incidents and-or disputes between the tenants, more occasions of requests for rent payment extensions (i.e.

I have nicely asked the PM on several occasions to be more proactive about updating me with the tenant when they fell behind on payments or when I did not receive my owner's draw on time.

I have on two recent occasions come across HOA CCR's that are so Draconian in nature, that if faithfully observed, completely block househacking as a strategy.

Lets just say he asked for my agent's fax number on several occasions.