I went there as a teenager 50+ years ago when you could just walk in and spend all the time you wanted to. So, I did. My art teacher loved Giotto and I guess taught me to. Still love him. Have taken several art history classes about Giotto and read quite a few books. Went again to the chapel in the fall of 2019 when we were staying in Padua for 9 nights, first for the usual 15 minutes which was nowhere nearly enough, and then a couple days later for the double nighttime visit which was great, especially because you get to have the chapel almost all to yourself between the regular groups of people. There is a lot to look at and I don't know how it is possible to do more than glance at half of the paintings in 15 minutes. My husband (nooooooooo fan of late medieval/early Renaissance art although he's seen quite a lot of it because of me) also really enjoyed spending a total of an hour with Giotto.
There's no point in taking the time to take photos because there are great ones online and those aren't at weird angles. I only took a few of specific things I wanted to remember to look up about later.
i'm pretty sure that if you booked two 15-minute visits during the day, you'd have to go out and then back in again between times in the chapel, and watch the little video again in the special chamber.
Take mosquito repellent if you decide to do the double evening ticket because you wait to go in outside at dusk.