Nope, sounds fair to me, although I think I'd allow more than 2 hours on days he's at home for the whole day, so weekends and school holidays - 2 hours would be very quickly used up especially if things like whatsapp to friends count and Saturday morning TV (not literal, but the concept) etc - isn't it part of childhood to loll around watching TV? They just do it with youtube now instead.
DS1 age 11 is allowed up to 3 hours per day. He has to do his jobs around the house (1 on a school day when he gets in at 2pm - not UK) and any homework and he can have time removed for poor behaviour. If he's doing something constructive like coding, homework, research, video editing, he's allowed to "double" the time so e.g. he can spend 2 hours on fortnite and then save the last hour to use as 2 hours coding. I sometimes even extend this if he's been proactive with his jobs/homework (ie, not had to be moaned at to get on with it at the last possible minute).
He also has the problem of not knowing how to entertain himself without the screen, which we talk to him directly about as I don't think this is healthy. He agrees it's not healthy, but doesn't know what to do about it. So I've encouraged him to try different things. He's also got ideas from friends at school - recently he's gone through speedcubing (modern rubik's cube), then card tricks, Patience/solitaire, trying to build house of cards, cat's cradle string thing, yoyos, then lately "Tischball" which is table tennis played with hands and a small basketball
- well - whatever keeps him interested in other things I suppose. (And honestly, 6 months ago this list would have seemed astonishing). For himself he's also come up with drawing comics/animation, so I've got him a couple of comic/manga drawing workbooks, and I gave him a template and insisted he write thank you letters to people who sent him Christmas presents including a little question and conversation in the hope they might write back and inspire a short back and forth (!) and during holidays I get him to do projects with me so we have done stuff like learn to cook simple food, tie dye some clothing, make some decorations/artwork for bedroom wall, make Christmas decorations. If you're not crafty, they can be more practical, but crafty at a child's level often doesn't have to involve much actual skill.
I'm sure at 13 they are less suggestible than they are at 11, but I have found that giving him actual tasks/challenges to do is much more useful than simply moaning on about the screens all the time. Yes, it would be nice for me and he really should be able to occupy himself by now, but at the same time it doesn't take a huge amount of effort/energy to come up with a challenge every few days/weeks, or provide him with a supply of activity books/sets/books to read, and once I've set an activity sporadically, he actually then will go off and do some other stuff by himself. It's just that initial transition away from "Make me entertained in a passive manner" to "I wonder what I could do now..."
Also, filling their time up with boring things like cleaning is a great way to get them to distract themselves into more interesting activities :o