I used to own a 2001 Hyundai Accent, with a 5 speed manual. It didn't have a tachometer. You learned what the car sounded like, and learned the shift points based upon the engine noise.

I could tell when it was idling high (for example on cold days) simply because I had driven it a lot. I didn't need a tachometer for that.

If your car is misfiring the check engine light should come on. These days a car misfiring can have serious consequences...