If you have a bit of a back and forth through sending snapchats to a girl, should one keep replying even if they have nothing more to say/she didn’t ask a question?

I’ve had girls complain I’ve left them on read before but I didn’t think that really applied to snapchats.

Do girls just expect a constant 24/7 back and forth? Alternatively should I just not open it until I have something to say back?

What do you guys do?