I watch a lot of films and series (mainly SciFi) at home and I find that when I start to get bored is when I'll pick up my phone and half-watch the TV. It's one sign of a great show that I'll be paying it 100% attention and not mucking around with a phone.
>>ndsipa+(OP)
I admit I find the long complicated series (yes, often SF or fantasy) a bit exhausting, have a definite limit, and I try to avoid interleaving too much.