Take a look at this screenshot from the arcade version of Tetris

Over on the right you'll see your 'stats', or a representation of the Tetriminoes you've had to deal with in Bar Chart form. My guess is that it's there if you're playing Single Player so that the right side of the screen won't be blank.

Now take a look at this screenshot from Galaga

Once you end your game, you're presented with your 'Hit/Miss Ratio', which tells you how accurate you were with your shots.

What do these things have in common?

Mostly that they don't really mean anything. It might be kind of interesting to know your accuracy, or if your Tetris puzzle gave you lots of Z pieces, but you can't really do anything useful with the data, and it won't really make you a better player.

So don't sweat it.

In Galaga you have these enemy bugs that take two hits to destroy.

They're the only ones in the game with a tertiary attack, instead of shooting or running into you, they can fire a tractor beam.

If they hit you with the beam, they'll capture your ship, and then attack you with it, it's dirty pool.

But!

If you can shoot down the enemy bug without damaging your ship, then you get yours back, and it's grafted onto your ship, doubling your firepower.

The downside is that now you're a much bigger target, and have two of your ships in play at the same time.

Is the tradeoff worth it? You'll have to decide that.

Just make sure that you don't let your last ship get tractored. That's a pretty lame way to lose the game.