For years what I did was try to collect a coin of every date and denomination from every country in the world. Obviously this is impossible, but while I knew I'd never finish it, I did it to the best of my ability. I had lists of dates that I needed from a wide range of countries and I'd go on eBay and browse for them, trying to check off a box. Eventually I realized this wasn't the best use of my time, money, or storage space. When you think about it, it doesn't make sense to spend $125 on a key date Portuguese escudo to complete the set when you already have 20 other similar coins and you have no special connection to Portugal or its coins. It was just checking off a box, and when you stop to question it, it doesn't make a lot of sense. So just like that, I stopped. I went through my collection, picked the best one or two examples of each coin and I sold the rest. Now I have a big box of previously used plastic pages and more shelf space. But there were some that I didn't get rid of. Some that I had gotten so far that it seemed harder to give up on it. After all, when you complete a set, suddenly it's a "thing," not just an accumulation. Now it's a set. But the urge to purge is setting in again. I'm starting to think, why am I keeping a full set of Australian pre-decimal coins? I started collecting them because I like big pennies and kangaroos, but it went well beyond that. So why not just do like with the others and keep a few of the key dates and better examples and get rid of the rest. It's harder when the set is complete, but I decided to do it. I'm going to start whittling down my Australian collection and we'll see what I move on to next. Here's an example of the Aussie pennies soon to find new homes. Next is half pennies and then the silver coinage.
The cycles of collecting are crazy, haha. If someone went through my collecting phases over my lifetime they might think I'm insane.
When it came to collecting sets, I came to the same conclusion as the poster in the OP, but all series except the few that interested me. Odd enough, the coins that grabbed my attention in that way were mostly gold. I collected sets of gold dollars, Classic Head $2.50, Classic Head $5 and the Indian $2.50 many years ago. I still enjoy looking at those sets so I have kept them.
As a side collection I collect Coin Club Tokens and Spinner tokens. There is no way someone can collect all of them, so there never will be a set. No set no stress.
Some of my most successful sets were the limited ones. New Zealand coins start in 1934. Australian coins start in 1910. And if you go up to decimalization there's an easy stopping point as well. Same for Ireland (1928-2000) and modern era Greece.
Purging is definitely a part of collecting. Sometimes you get too many of something and realize that a few examples (more of a type set) are just as satisfying as having one of each. Plus the sales of the extras can be used to add new coins.
This is exactly what I've been doing. Type sets and funding coin purchases from the sale of old coins.
I was much in your situation before I settled into a niche. I have found I own fewer coins, but enjoy the ones I have now more. Even sometimes, I think the area I've chosen is still too broad.
