I can help you identify high-variance (volatility) slot machines. A high-volatility machine will have a low hit frequency. The following are my general rules for identifying low hit frequency machines:
||The higher the lowest reward on the paytable, the lower the hit frequency.
Looking at the paytable is one way to identify low hit frequency machines. Although we can't calculate the exact hit frequency of a machine by inspecting its paytable, we can make a guess about what the hit frequency is relative to other machines' hit frequencies.
To estimate the relative hit frequency of a machine from its paytable, check the value of the lowest reward on the paytable. As a general rule, the higher the lowest reward on the paytable, the lower the hit frequency of the machine.
A machine whose lowest pay is a push or two coins can afford to pay you more often than a machine whose lowest pay is 10 coins.
IGT's Lucky Sevens is an example of low hit frequency machine on which the lowest reward is very high. The lowest reward on this machine is 10 coins. I once went 72 spins in a row without a hit on a Lucky Sevens machine at The Desert Inn in Las Vegas.
High lowest rewards always indicate low hit frequency machines. Unfortunately, the reverse is not true. That is, paytables with low lowest rewards are not necessarily high hit frequency machines.
||The higher the multiplying symbol, the lower the hit frequency.
Machines with multiplying symbols tend to have lower hit frequencies than machines without them and the higher the multiple, the lower the hit frequency.
Machines with multiplying symbols have what I call "hidden paytable entries." The winning combinations with the multiplying symbol aren't listed on the paytable, but the payout program has to account for them. An example of a hidden paytable entry is the Double Diamond symbol and two 7s on a Double Diamond machine. This combination does not appear on the paytable, but it is a winning combination and the payout program has to account for it.
Consider a Double Diamond machine. Each doubled hit can be replaced with two non-multiplied hits and the payback will be the same. Similarly, each quadrupled hit can be replaced with four non-multiplied hits and the payback will be the same.
Now consider a Ten Times Pay machine. Each hit multiplied by 10 can be replaced with 10 non-multiplied hits and the payback will be the same and each hit multiplied by 100 can be replaced with 100 non-multiplied hits and the payback will be the same.
There are some machines with multiplying symbols that have good hit frequencies but, more often than not, machines that have multiplying symbols have lower hit frequencies than machines that don't have multiplying symbols and the higher the multiple, the lower the hit frequency.
||IGT's Red, White and Blue Sevens and Bally's Blazing Sevens are low hit frequency machines.
I call this way to identify low hit frequency machines "Mama's Rule," because these machines are low hit frequency machines "because I said so."
You can't identify these machines as low hit frequency machines by looking at their paytables. Their lowest payouts are low and they don't have a multiplying wild symbol. Nevertheless, these machines are low hit frequency machines because they favor mid-range payouts of 100-300 coins over payouts of fewer than 100 coins. And you have to remove a lot of low payouts in order to pay just one more mid-range payout.
The most famous, and most popular, machines of this type are IGT's Red, White, and Blue Sevens and Bally's Blazing Sevens. The real excitement on these machines comes when you land a combination of Sevens on the payline. And if you watch a bank of these machines being played, you'll notice that the Sevens come up pretty frequently, and the lower-paying bar combinations come up less frequently than on higher hit frequency machines.
Although you can't tell that these machines are low hit frequency machines before playing them, you'll know pretty soon after you start playing them. If you track your hits while you play, you'll have a good gut feeling for the true hit frequency of a machine after about 500 spins and a very close estimate of the true hit frequency of a machine after about 1000 spins.
Now, why would you want to play some of your bankroll on a machine with high volatility? Because even though your chances of getting a hit are lower on the high-volatility machine than on the low-volatility machine, the hits tend to be bigger. You're giving up a bit in your chances for getting a hit in exchange for winning more.
The flip side is that cold streaks on high-volatility machines tend to be longer, so you need a larger bankroll to be able to keep feeding the machine and see you through the cold streaks if you want to play most of your time on these games. Playing more time on the low-volatility machines, on the other hand, tends to keep you in what we used to call "tray money" and often gives you more playing time for the same bankroll.
There's nothing wrong with your plan. Limiting your exposure to the high-volatility machines decreases your bankroll requirement.
I frequently do something similar. I take a small part of my bankroll and use it to play one coin per spin on a $5 machine. Like you, I'm trying to catch lightning in a bottle, but I'm going to spend most of my time on a more affordable machine.