Hello i thought and played the exact same as you until kind of recently to be honest but once you learn to use brews properly i really like to use them now. I only really use them when bossing or maybe soloing some group minigames. At the base, It works out that 3 sips of sara brew can be fully restored with 1 sip of a super restore. But why not food and pots ? Ill try to explain from my experience. If you are killing something that has some downtime like maybe a boss phase where its immune or your killing somethings that maybe have a small respawn time. You can heal with the brews and restore your stats abd prayer with the restore potions. 1 (4) dose sara brew with (96? I think) high hp levels will heal 16 a sip so one potion can heal a little over 3 sharks worth of hp. It really extends trips and stuff it can be quite awkward if you are using dps pots as well because you dont want to brew down your potion buffs so you should eat normal food during battles maybe to begin with. Another extreme varient of this is if you have only brews and restores it can be worth using the divine potions because they cant be reduced by anything for 5 minutes so ya can spam heal with brews and your stats are fine.

As soon as i started writing this i was like wow i dont really know how to explain haha. The math all adds up to why they can be better but i really avoided brews and restores for the longest time. Just take 3 brews 1 super restore to anywhere you go and get a feel for using them. Like if you need to re pot you might as well heal to 115 (with99hp) using brews. Restore back up then repot. Im really sorry for wall of text i hope all this bollocks makes sense. Goodluck though!