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...But it was fun and gave some enjoyable heartpalpitations...
It also leads to confirmation bias. Confirmation bias misleads hobbyists and causes them to waste time and money. They make horrible buying decisions and worse of all, the disappointment can cause them to leave the hobby.
Here is what NOT to do. Use
ebay listings, sorted by highest first, to lookup a stamp with a similar design as a stamp in hand. See stamps listed with huge numbers. Excitement builds. Do a bit of research and read that the rare stamps are 19.75 x 22.25. Measure the stamp design; excitement builds to very high levels.

Come into a community like this and tell folks that they have a rare stamp; often they will argue for days and days. Sometimes they blame the community for being 'kill-joys' or otherwise 'crushing their dreams'.
None of this is fun or enjoyable for anyone; especially when a quick forum search will reveal 100+ threads which unfolded as outlined above.
It is important that hobbyists be open minded when identifying stamps. Our hobby has many things to offer, things that can be delivered without odds longer than winning ten lotteries in a row.
Learning to quickly make an accurate identification of a stamp is a core competency of the hobby. Sitting in front of a table full of stamp and wasting time thinking each one is rare steals time that could be spent learning about the history and culture that each stamp represents.
Lastly, our hobby does indeed require a significant investment in education. No one can learn this hobby is a few days, weeks or months. There are no real short-cuts to gaining the decades of experience that many in this community process. But communities like this or your local stamp club represent a wealth of knowledge which many are willing to share.
Don