I usually have Shadowheart in my party so I use guidance for basically everything and adding that 1d4 to Astarion's lockpicking check feels honestly gratuitous at this point (I still do it tho)
I just use a 2nd lvl spell called Knock, why try when you can just succeed. By the time you see 30 locks spending some 2nd lvl spells for knock should be totally fine.
Caster with Knock is is a solid alternative, although I've found myself needing to rest because Gale has spent all his spells on unlocking stuff an unfortunate amount of times. :P
My lore bad has expertise in sleight of hands, the 18 dex gloves and knock. anything over 20 gets a knock, anything under gets the easiest roll of their life (13-17 bonus by now)
On the other hand, my Warlock who coincidentally has the best dex in my party, has been burning through Thieves' Tools like there's no tomorrow, since no one has Slight of Hand and I can't be bothered to go back to camp for Astarion unless I'm doing stuff I know involves him. :P I miss Shadowheart having the Urchin background. :P
No but like, sometimes you'll succeed a roll and a message will pop up going "THIEVES' TOOLS USED"
It seems to happen when I roll something that's just a bit more than the DC, so like, a lock that needs 20 and I'll roll 21, it gets consumed. Whereas it seems to happen less when rolling like 10 more than I need.
But then sometimes even this observation doesn't seem to apply.
Are you sure it's actually consuming the tools when you get the message that they were used? I noticed the same message and had the same concern but when I started paying closer attention to the number of tools I had in my inventory it only ever went down if I failed a lockpick. If I lockpick and succeed I get the message, and sure I did use my tools, but they remain in my inventory.
You use thieves tools every time, but they break if you fail. That's the easiest way to think about it. That message popping up doesn't correspond with breaking a thieves tools in my experience. So you get the message, but the total available remains the same.
I think that's the same message as "used old key". It doesn't get consumed, just informs you how it was solved. But I never paid much attention to it, so I might be wrong.
I know exactly what you mean and it happens to me. Pick a lock and succeed on the first try and get the message it consumed one. Happens randomly for me like you.