takes about 20 tries until it car starts...but rough idle

[MK1888]

A starter can have a bad spot on commutator, where little or no electricity flows through the contacts. And when the solenoid pushes the gear out it moves the armature just a tiny bit, enough to get to a good spot.

Yep, that can happen. It could be your problem, but it sounds like you have a few problems.

Keep in mind that the starter only turns the engine, it's not reponsible for whether the engine starts. If you turn the key and the starter doesn't turn the engine then you've got a problem in the starter-solenoid-battery-ignitionswitch circuit. If the starter turns but the engine doesn't start then you've got issues related to fuel or spark or timing. You need more investigating.