Well, Herb Simon once said that the fundamental scarcity in the modern world was scarcity of attention. Why might this be true? applying some Ec101 thinking: if there are demands for everybody’s attention, there is certainly not as much supply. So here is a rule of thumb by Hal Varian to keep in mind:
"if you want someone to pay attention to you, you have to give them a reason to do so"
Let it be for conferences, thesis seminars, friends, and even flirting: it applies in the same way. Finally, here's another interesting quote by Simon that explains why:
What information consumes is rather obvious: it consumes the attention of itsI found it astonishing true
recipients. Hence a wealth of information creates a poverty of attention, and a
need to allocate that attention efficiently among the overabundance of
information sources that might consume it