This may have been answered previously but I have just missed the answer......Watching the Cohh stream he kept running back to Sprig and his preception interface kept popping up with just the Farewell as a choice to answer. I want to assume(hate assuming) that there will be a way to keep this from happening after we have gotten past a certain point in the questline. The preception system while very cool and unique will get old real quick if it is popping up non stop with useless quest we do not want to take over and over again.
Yes. I believe it was something like a timer where if you chose not to interact with a perception ping, or intereacted but didn't choose to follow the quest it offered, then you wouldn't see the ping again for some time period of hours or days. It was also suggested that different categories of perception pings would have different length timers. And then as Vander says, you could also just toggle perception pings on/off as you wish.
I would assume that certain perception pings that deal with storylines would stop after you had progressed past certain parts of the questline. For example, after interacting with the spriggin I would assume that the pillar with the stone would deactivate because you had progressed past needing that perception ping.
I know that they said in a previous stream that the system would have timing limitations placed on some of the pings as not to constantly be going off and that there may be settings added that would allow for the player to have some authority over how often the pings went off.