2005 Chevy S-10 Blazer: parking brake slips
 

I bought the truck used,the parking brake cables were frozen
So I sent it to the shop and had everything fixed except new brake shoes
because the old ones weren't worn...
Parking on an incline it slipped. it was useless.
So I had new Wagner ceramic brake shoes put on.
They held the 1st day.... 3 weeks later I tried the parking brake on a hill and it slipped
again. Is there a better brake shoe pad out there than ceramic?

Maybe just tighten the e brake line a little more. They might not be adjusted enough on the rear end... mines the same way, but I'm too lazy to adjust it, and I haven't come across an incline I needed it yet.

+1 on adjust them up.
Besides parking brake use park or if a manual leave in a lower gear.
Turn tires to curb so if vehicle moves curb will stop it.
I never depend on just parking brake only to hold vehicle on a steep hill esp if it's down hill in reverse

I've always heard to leave a manual in gear, but I never liked doing that. Just depending on engine compression at that point. Always been a parking brake guy, myself

I agree with you up to a point but I like both E brake and in gear as a pair ....
As far as compression bleeding off and not holding think of trying to tow start a vehicle that has been sitting a week or two, In a higher gear engine rolls over and starts -
Drop it into a low gear and no matter how long it has set and compression may have bled off the tires skid and engine won't turn over ...

My problem with leaving it in gear, is I'll forget, and dump the clutch after I start it, thinking I'm in neutral. Then it lurches forward and dies, and I look like a dummy. I always shake the shifter to see, but the one time I don't... Lol.

Nah, either way is fine, as long as that's your habit and you do the same thing every time, I think. My dad was always a leave it in gear kinda guy

I live in the mountains... so I guess you have no experience with hills.
What's even more irritating is that it only slides down when the truck is
pointed up an incline but it doesn't slide when it's pointed down an incline.
I've got the cables adjusted as tight as possible so I have to use all the force in my leg to push the pedal all the way down. My mechanic says that's just the way it is and it can't be fixed. A parking brake that doesn't work can't be fixed?? A parking brake can't be fixed? You have no idea how infuriating that is. I want my parking brakes to work: period. I'm looking for other Blazer owners who had the same problem, I can't be the only one; unless it's the fault of the brake shoes but that makes no sense: A brake shoe that works in only one direction, but doesn't work in the other direction!? WTH!

Well you quoted Don but I'll answer.
I live in Wyoming the whole state is hills and mountains.
ALL E brakes no matter what make of the vehicle work better facing down a incline and not as well in the reverse - just the nature of the beast.
As every scenario's change you need to adapt to them - hence turning the wheels, leave in gear, leave in park and others as I stated above.
EDIT - I guess I should add that with the newer brake systems this scenario is not as pronounced as with the old school drum and shoe system but under certain circumstances even the new style E brake will not hold vehicle on slopes and inclines.

I have plenty of experiences with hills, as I do road trips through the Appalachian mountains almost yearly, and a lot of camping I do here in canada is hills too, with a camper being towed.

Parking on the hills themselves, never had an issue, face forward, wheels turned to the curb, ebrake applied.

Only other think I can think of, is the pedal assembly itself, i had to replace mine because it didnt lock into place, but I'm not sure about any adjustments on it.

Best of luck with the hills!

If the brake aren't working as good as you'd like, you can also come up with adjustable stick, wedge between steering wheel and brake pedal. Or maybe even a wheel block?