Yes, the streetcars are always running except when they stop to let people on, they don’t expect you to jump on when it’s moving as that would be very dangerous as well as inefficient.
During the weekdays they run about every 5 minutes going toward downtown. Going from downtown to uptown there are often delays because more people get on downtown toward uptown because the streetcar has more stops to make.
Sometimes toward uptown you might wait for quite a while and then suddenly you see like 3 streetcars one behind the other with the one in front being the most full. It’s OK to let that one skip you and catch the ones behind. If you have the metro app on your smart phone you can track when the streetcar will get to you.
It helps if you have a book to read on your phone. You can get my book about New Orleans Your Own Personal New Orleans Tours to keep you company.