The current state of sentry wards is just stupid. They are OP.

Four years ago I made a post where I suggested a limited stock for sentry wards. It got downvoted and everybody told me how dumb this idea is. I think we need another adjustment.

Over the past patches sentrys became very cheap (100g > 75g > 50g) and although a small nerf the duration is still extremely high (7 minutes). On the other side, observer ward gold and xp bounty was buffed significantly, making dewarding in addition to the vision aspect ridiculously valuable.

The result? There is no downside of spam-buying sentrys. Or the other way around: Your are stupid if you don't buy-out all sentrys. If you look at pro-games, both teams pretty much always buy the maximum possible sentry amount. It doesn't matter if there are invis heros in the game or not (example).

TL;DR
– Sentrys are OP
– Dota is a game about making decisions. With sentrys there is only one correct decision: Buy them all. If you don't, it's a mistake.
– Solution: Reduce the duration (240s) or increase the price (100g) so you actually have to think if it's worth buying a sentry or not.