I think the iphone does a lot more in the background than you might consider initially. Here is an experiment to try. Use your phone as you currently do, but turn on airplane mode when you aren't otherwise using the phone. Leave it on overnight too. You should only lose a few percentage overnight on airplane mode even with an old phone.

My iPhone today last for less than a day while I dont watch any video on it, In fact, i barely use it currently, and it still drains batteries in no time.

Odd. I wonder if you have some apps updating in the background a lot.

Both my personal and my work iPhones are two-years-old, and both will last several days even with audio streaming.

I put my work phone in its drawer last Thursday, and when I took it out on Tuesday, it still had 11% left.

Try disabling Bluetooth from within the settings. My iPhone and iPad would drain like 50% of their batteries overnight if I left Bluetooth on. Now they drain about 10-15%. Still a lot for devices doing nothing, but better than before.

The drop down menu doesn't actually disable bluetooth so that alone won't work.

My 7 year old iphone lasts almost two days if I don't do anything too taxing (i.e. video). I don't think I do anything special. I guess YMMV.

How old is your phone/battery? When you say less than a day, do you mean 24 hrs or the period of time you're awake?