My daughter is 2.5 & to be honest, has a fair bit of screen time but not sat in a high chair, that seems very restricting! Fine for 30 mins or so while mum/dad is cooking but not for hours.. I think by quiet time, it’s quiet time for mum not child 😂 But equally, each to their own, it’s their kid! I wouldn’t worry about it. You parent your way & they’ll do theirs. I think so long as TV isn’t used literally all day in place of any other activities and interaction from adults, then the kid will ultimately be fine!
I find parenting with zero screen time a bit peculiar in 2019. Screens, TV shows & apps are not the devil.. they are all part of childhood just as much as painting, drawing, reading & playing. And goodness, don’t be a saint. Use Hey Duggee as a chance to have a break yourself!
I’d say for example, on my days at home with my DD, she’ll watch TV in the morning when she wakes up at the crack of dawn! 
Later on, we go out and do an activity every morning - softplay, toddlers, park, library, gymnastics, messy play.. when we get home, I pop something on her iPad in the kitchen while I make lunch for us. We have lunch & she naps. After lunch, we tend to stay in and play or do baking, painting etc .. some days she’s keen to do these things, some days the telly is on all afternoon. I don’t worry about it. I go with her mood. It often depends on how busy she’s been in the week! Again, sometimes she just needs a quiet afternoon flopped on the sofa just as we do as adults! I use the time for precious cuddles as usually she’s too busy for cuddles 😄