How many of you schedule your ads to only show during peak periods?
Should scheduling your ads be taken seriously?
Until now I have been running my ads 24/7 but I've been wondering If this approach wastes ad spend.
Looking forward to your replies
Let your data decide.

Unless it's a huge drop off, or needs to be dayparted, I'd be hard pressed to say only run on peak hours
Testing is key in every situation, even if you're 99% sure it won't work, 1/time out of 100 it could make it a big campaign.
If in doubt, test, then test some more.
Personally, I don't think it matters that much... I used to run a scheduled campaign. Everything is ok until one day I forgot to schedule one ad set. It turned out that this ad set did not perform differently from other scheduled ad set. So yes, data can tell. 
Heres an networks point of view... If you have a personal AM, ask them for advice 
AMs have A LOT of previous data and experience with the products and markets, they can better advice you on when its most productive. Some products may even come with time specific requierements.
If you have an AM, make use of that premium attention and inside info.
Dayparting hasn't made much difference for me either, definitely give it a shot and test if for a few days but in general letting it run 24/7 will have the same results...
same here, obviously you're gonna notice a drop off in # conversions and conversion % at night (except if you're doing some adult lullz)- but you'll be getting only a bit of traffic. Sometimes I wake up to 250,- daily budget campaigns having spent only ±5 bucks over the 23:30 - 06:30 period, same with the 'dinner time dip', where you'll be getting a normal amount of traffic, but it's just people browsing online because they're eating- they're not gonna convert unless you make them feel guilty about eating (weightloss lmao)
If you do, split-test the day-parted vs non-day-parted.
FB is much better at ad pacing these days but there may be benefits to running 24/7, e.g. the ads get higher CTR in the early morning (but fewer clicks), this helps spearhead the ad delivery into the day, etc.
Short answer, no. Unless there's a limitation on the advertiser's site. e.g. Pay-per-Call campaigns that only allow weekday traffic.
I believe optimization algorithms (i.e. oCPM) almost always take into consideration time as a metric. So i believe this might be a waste of time. But like everyone said, test.