When does sharding a database become more trouble than it's worth for scaling?

Hey everyone, I've been thinking about database scaling and sharding. People often talk about it as a way to scale horizontally when you have huge amounts of data or lots of writes. But, wow, it really makes things complicated. Schema changes are a nightmare, doing queries across different shards gets tough, and resharding, well, that's just a massive project. So, when do you all think the effort of running a sharded database just isn't worth it anymore? When should you look at other scaling ideas or maybe even a totally different kind of database?