“subway systems here are pretty safe”
New Yorkers pretty much must use the subways, except for the super-rich that can afford private car service.
The subway can be very fast. Get on a train in the right direction and look at a subway map. If you are on express, ride it as far as you can to your destination. If you need to get a local, transfer at the last shared stop possible.
Express trains are about three times faster than locals.
Yes they are. For benefit of NYC tourists, the express tracks are in the middle. The outer tracks (uptown or downtown) are the locals and stop at every stop.
They are worth waiting for even if you see locals constantly coming in. Just check the stops on your subway map and take the express stop nearest to where you want to go. It's usually worth just walking to where you need to go from the nearest express stop.