Important things to keep in our minds:
Looking at a poster is not meaning they read it.
Staring at a poster also not mean they read it.
Isn’t it also same for us when we are reading books? I remember times that I read the same page again and again and again. Why? Am I looking somewhere else? No! Am I using wrong lines? No. Is my eyes having problems while seeing the sentences and the lines? No!
We know that seeing is not equal to reading. So we should be sure that our posters consists of brief information and can be seen easily (even at night, so we will arrange the lighting sensitively. It won’t be as simple as turn on and turn off, but you could also arrange the level of its brightness according to your own context and environment). About being consize we will ensure that there is Qr code on our posters so if they need additional information, they can scan it, or if you choose the expert of the event organizer who have comprehensive knowledge about it, if they have questions, after few minutes that person with the remote controller can be seen to them and ask them their questions:)
It seems sustainable at the moment.