Sewingmachine needles by Schmetz are well known and of premium quality
Use a leather needle only for thicker leather, the triangular point cuts through the leather and when your leather is thin it can tear. For thin leather and immitation leather we use a superstretch or special needle (HA x 1SP)

These needles have a cutting triangular tip. A half triangle point to cut through the leather more easily. For straight seams in leather, hard immitation leather and other stiff materials. Not suitable for woven fabrics or gauzy materials

In this PDF you will find a combination table for fabric, sewing thread and needles: 
Sewing thread, needles combination PDF

TIP: a needle can work for 8 hours, after that it needs replacing

That does not mean you have to replace it after one day of sewing. Look at is this way: should you press the sewing machines pedal and stay like that for 8 hours, so the machine does not stop sewing, after that the needle is blunt
The easiest way to ensure you are sewing with a sharp needle is to insert a new needle with every project..