In a buy/hold portfolio, how often should/does one sell/1031 exchange properties?  Do investors tend to hold on to properties for more than 10 years?  Is there a right/wrong way to go about it?  I imagine some properties will perform better than others overtime..?

@Mark Douglas

Depends on your goals, where your properties are, what your current ROI is, and if you can get a better ROI elsewhere?

A simplistic example: You have a $100,000 property that is rented for $2000 per month. If your property appreciates to $150,000 in 10 years, and your rent is at $2300 per month. Can you sell, use that equity to buy another property for $150K, or leverage it with a loan, for a MF that rents for $4000 per month? 

Some investors will also sell dogs out of their portfolio so they can deploy that cash to make more money in another property. 

@Chris T.   thanks Chris, that makes sense.  I only have one duplex so far, but just trying to get some sort of mental plan going lol.  Would pulling out equity (cash out refi or heloc) have the same effect as selling and buying another property?

If you have enough equity in your house or investment properties, you can get a HELOC on them. Use that line to pay cash for a property, and do a BRRRR.

No, it is not the same as buying another property. 

If you only have 20-30% equity, then it makes no sense to refinance. Unless your mortgage interest is really high or you want to extend your term and get lower payments.