When my boy was a puppy we really took a no-nonsense approach with him jumping up on counters, tables etc (he's a GSD). It worked really well but recently he has started jumping up on counters but only when I'm not in the room, he knows he's not allowed. I keep both the kitchen doors open so can hear him when he jumps up from the living room. I've been giving timeouts but it doesn't seem to be working, not sure he connects both actions.
Would be really grateful for any suggestions- he grabbed a knife with leftover cheese the other day! Some family members fail to remember to put things away which doesn't help.