For example, a Roofing contractor should be able to quote you a rough price over the phone with some basic information (size of roof, slope of roof, type of roof, etc.)...Put your spreadsheet to work and start practicing estimating and analyzing deals. 

In the flipping scenario, the flipper is likely adding value by cleaning up, rehabbing, and marketing the property, and simultaneously is relieving the seller of his/her problem (the need to sell the house).

This presented a problem as the bank didn’t like the idea of me simultaneously financing another property, so I hurried the process and delayed the third from going to the bank.

However, in practically every jurisdiction, you are not forced to belong to the S8 program.

For me, diversity in multifamily asset class would be nice in theory, but in practice it is way, way downstream of finding decent deals. 

Disclaimer: While I’m an attorney licensed to practice in PA, I’m not your attorney.

Talk to all the sellers you can, even if you don't plan to buy, because you need to practice a lot to get good.

Also, I recently discovered real estate photography so I’m currently learning and practicing to build up my skills in that.

Would it be better to spend my time on some formal education or simply do more flips to gain more practical experience / knowledge?

I’ve been doing my research, crunching practice numbers, and learning the market.