or is this just a bunch of baloney?

No, averages are real, everything has an average. But it cannot be used to increase the accuracy.

For example, in every 18 spins,

**on average** there will be exactly six numbers from dozen 1, six numbers from dozen 2, six numbers from dozen 3. Or

**on average** there will be exactly 9 red numbers and 9 black numbers.

So after 9 spins and 7 black numbers, can you bet on red to catch up with the average? No you can't.

Sometimes in 18 spins you will see 12 blacks and 6 reds, then in the next 18 spins you will see 12 reds and 6 blacks. This is the variance of random. But the average will still be 9 for both colors.