I don’t use All. It’s completely devoid of interesting things for me. I tend to use Top Day Subscribed so I’m looking for stories that have some traction and a conversation going on. Doing that with a large number of subscriptions means the most popular topics overwhelm the less popular topics. All I’ll see is Memes, but never my sub about scuba diving. If the scuba diving community is split across 7 channels, but memes is just one big channel, that just gets worse.
I was a big user of multireddits. That allowed me to group subs together for more niche topics, and see what was top in that area. I think Lemmy isn’t going to cultivate smaller channels without having a way to get them appear regularly to users.