The net library is much better than networked variables, it is faster, the space limit is Much higher, and NWvars queue up(which can cause problems in servers with around 40+ people) while the net library sends information straight to the client right then and there.
You should learn how to use the net library, and use it for any future networked objects. Leaving a few old style NWvars won’t hurt any kind of performance, which is a good idea if you do not want to go through the headache of converting over entirely to the net library.
-Network things only when needed. Such as if you need all players to be aware of a variable unique to a certain player(cash/wins/ect) and take for example the only way to see another players cash is by opening up some menu. Network stuff then, instead of sending a message to every client every time a player earns/loses some cash.
-Try not to get to fancy if you are new to networking things. Although you can do things like creating wrappers, which is basically like making a framework for networked objects. This would be useful but a little complicated because it can help you manage your networked messages with ease.
-Don’t stress things. As long as you are sending networked variables as little as possible but only when needed you will have no problems at all.
I have never seen this tutorial before but it looks like it has all the information you should need.
Tutorial: Using The Net Library