Multitasking feels efficient but for studying it is almost always bad, and the science is clear on this. Your brain cannot truly do two thinking tasks at once. What it actually does is switch rapidly between them, and every switch costs time and focus. So studying while texting, watching videos, or checking social media does not save time, it makes the studying slower, shallower, and easier to forget.
The hidden cost is called switching cost. Each time you jump from your chapter to a message and back, your brain needs time to reload where it was, and you lose the deep focus that real understanding needs. Students who study this way often spend three hours to do one hour of actual work, and they remember less of it. It also trains your attention to be jumpy, which makes focusing harder over time.
The better approach is single tasking. Give one task your full attention for a focused block, then switch fully to the next thing, including breaks. When you study, just study. When you take a break, actually rest or check your phone freely, then put it away again. You will finish faster and remember more. The only kind of multitasking that is fine is pairing a mindless physical activity with thinking, like walking while listening to notes, because walking needs no real attention. Two thinking tasks together, though, always cost you.
Example: Studying a chapter with your phone buzzing beside you might take three hours and leave gaps. The same chapter with the phone away often takes one focused hour and sticks better.
One practical tip: Separate work and breaks completely. Full focus while studying, full freedom during breaks. Blending the two just weakens both.