There is a lot of focus on the max. buy-in. For me, establishing a minimum buy-in and getting the blinds right is more important. I am very familiar with the kind of $20 games other members have described elsewhere on this site. I played in a long running .50/$1 home game (The blinds were originally .25/.50) that had a fixed buy-in of $20. Same for re-buys. Over time players became more aggressive with their pre-flop bets, to the point where $5 opening bets were common, even early in the game. Such a bet would induce a fold or two, which meant you would go to the flop with $30 or $35 in the pot.
That game typically had 9 players and we would have anywhere from $800+ to $1000 on the table. (40 to 50 buy-ins)
I played in .20/.40 $20 buy-in NLHE/Omaha-hi game last year where the pre-flop action was also very aggressive.
This game was by far the most unconventional game that I have ever played in. Players would bring their winning lottery tickets to use for calling bets or buying chips. There was no predictability as to how much money would be on the table. The amount depended entirely on mill workers shifts and whether they received their bi-monthly checks that week along with seasonal employment. Normally, we would have 8 players with $650 to $800 in play. Other weeks we would have 10 players and as much as $2000 on the table. Players who didn't work at the mill would often re-buy for $40 regardless of how much money was out there. The mill workers would typically re-buy back in for $60, sometimes more depending on the amount of money in play and if they got their checks that week.
We had a small case of dice chips with the various colors having an assigned value of .20, .40, $1, $5 and $10, which covered games up to $800 and .20, .40, $1, $5 and $20 the weeks where we had two or three players from the mill. There were nights where we had several hundred dollars in cash and over a $100 worth of lottery tickets on the table. Players who won pots would have to sort out all three currencies.
Not uncommon to see pre-flop bets of $7 or $8 once players had built up their stacks. Again, unless someone had just rebought in and wasn't the first to act, you could expect nearly everyone to call.
Seems like short stacked poker is popular. I don't mind it, except when the pre-flop action gets out of hand. To me, poker is about making good decisions. You can throw out a lot of the fundamentals regarding skill when aggro players can buy in short and reload cheap.
Don't misread me. Both games can be quite profitable, but you would be wrong in thinking that you are going to become a solid player by playing in these kind of games. I invite you to buy into a $2/$5 game at the casino if you believe otherwise.
Based upon my experiences, you build skill by playing in games that have a minimum buy-in of 100BB's and where pre-flop bets of 10-15 or 20x the big blind will thin out the field.
My 2 cents.