The lifespan of brake pads is not only dependant upon environmental conditions but also very much upon what is put into them.
I'm compelled to point out there is a massive difference between the compounds that manufacturers put into brake pads. I've no idea what compounds are actually in them but I'd describe some as "rubbery", some as "gritty", and many in between.
I've had brake pads that, no matter what I do, will shudder or squeal - I dare say they have too much rubber in them - whilst other pads grind away my rims faster than they wear away themselves. Meanwhile some work well in the dry and bad in the wet, some the opposite.
"Normal" will vary according to your environmental conditions. Rain-Wet is always more wearing on all pads. But my primary point - brake pad compounds do vary wildly.
Sounds like you don't use the front brake enough... that's where all the stopping power is: weight shifts forward, tire presses down more making more contact with ground, providing more friction with ground, stopping you faster. Favouring the rear brake makes you not slow quickly, squeeze harder, wear more pads, loose traction - all bad. Where safe, practice using ALL front brake and not using the back; do this until you fully appreciate the value of front brake as you enter a corner and transition to back brake only when you're past the apex and sensing trouble.
Focus on teaching yourself where in the corner you want that transition - from predominantly front to predominantly rear - to occur.
You will need to constantly tighten up the pads - get to know that adjuster - and maybe even reset the cable once to get the full life of the pads. Rain, no matter what the compound will burn brake pads. If you live in a wet place there's no getting around harsh pads and replacing both the rims and pads often.