Yea, I agree the channel is a mess these days. Like most in the documentary section. None of it is really educational. I just like switching it on from time to time after work to watch Mythbusters, which is now fast becoming tiresome.
Hence I don't watch TV. I only watch films these days. Adverts drive me up the wall. Had I lived on my own right now, I wouldn't bother with a TV subscription.
That is what PVR is for. Set shows with potential on record, watch a few mins then delete if rubbish. If decent, series link it, then every advert can be skipped when you watch it at your own time

Honestly though, Discovery have gone down the drain. All these documentary caters either nut jobs (Aliens on History Channels) or Augmented Realities crappola. If it weren't for shows like Food Factory / How do They Do It and occasionally Tech Toys 360 along with some of those missed BBC Doc repeated on Eden, I rarely turn over to Documentary channels.