Aside from the limited amount of info available from the leader boards, is there any way to tell if the person you are about to hit is shielded? I don’t use line, and was wondering if there is any other way to know.
No, not really. That’s why it’s customary to wait a little while so the target has a chance to shield up, but of course you don’t always have that luxury…
Try skipping to see if you can find them again. If not, then they’re shielded. 
Seems like a waste of Iso…
I think she was being facetious.
Better way is to hit them then skip to see if you can find them. If you can’t then they are shielded. If after hitting you find them again that could be a cached queue so hit again. If you find them again after the second hit then they probably aren’t shielded.
I’m so helpful today! 
Customary? Whose custom? No one ever waits to see if I’m shielded.
How long are you usually unshielded?
Longer than “a little while” apparently. And if I am supposed to wait to make sure other players are shielded, then I’ll get hit even more. When I get over 800 pts, in fewer than 2 matches I get hit multiple times.
I see an 8 hour cooldown listed on the shield screen. I have no idea how that mechanic works but how can people shield hop if you have to wait 8 hours?
There are 3 different shields, and the cool down is for a specific shield, not shielding in general. For example, you buy the 3-hour shield, and you have to wait 8 hours before you buy another 3-hour shield. Meanwhile, who can still buy either the 8 or 24-hour varieties.
That’s why you search for targets while shielded, wait a while so they have a chance to shield, then unshield, hit the targets fast and then reshield.
As mentioned though courtesy is a luxury you cannot always afford. Once you are past your equilibrium point you hit what you can, obviously.