You're on point, these help mechanisms should be rare and few, or they would be a nuisance as well.
The problem with forced screen of tooltips in the very beginning is that you haven't had a chance to explore the app yet, and so it's hard to mentally assign importance to them. And later, they're gone.
The problem with forced screen of tooltips in the very beginning is that you haven't had a chance to explore the app yet, and so it's hard to mentally assign importance to them. And later, they're gone.