That's one of the main reasons I use it that way. Aside from that, it's been a better experience than subscribing in YouTube, when I did that, there'd be a number next to the channels but I could never decipher exactly what it meant, it certainly wasn't just new uploads.
Then why did you make the remark about 'double subscribing'?
Also, there's a good reason for subscribing to channels: it actually help the channel creator because the subscriber number (which is what that number is) feeds into their algorithms regarding reach.
