Yeah the flow of time here seems kinda fucked. I'm guessing the author is having difficulty fitting the entire day into 4 panels while also conveying enough information for character and plot progress.
In Day 15 the author used a neat trick of using a flashback to squeeze out 4 extra panels about the date, but the debt obviously caught up to him.
Maybe with a little bit of suspension of disbelief you can pretend that days have passed, but the MC not noticing that his phone is gone for 3 whole days might be a bit too much.