@Jono
How fast the brightness will deteriorate will depend on your usage. There's no exact number of hours. For proper monitors, it's usually after 3 years. And even so it's not like a drastic drop. You won't notice the drop because it will be long process. But even when brightness drops, you can still increase the brightness because you're not using it at maximum brightness in the first place anyway.
@Jono
How fast the brightness will deteriorate will depend on your usage. There's no exact number of hours. For proper monitors, it's usually after 3 years. And even so it's not like a drastic drop. You won't notice the drop because it will be long process. But even when brightness drops, you can still increase the brightness because you're not using it at maximum brightness in the first place anyway.