(I'm new.) I'm loosing points on Quentin's quests. Is this usual, or am I just having a run of bad luck?

The main draw of Quentin's quests is that they have a chance to give out Mage amulets like which you can turn in with the mage for a chance at tomes, which boost battle stats.

There's a 50k sP cap on the items Quentin can ask for, but holiday items often get inflated to around that price for that reason, so they often don't give out enough pure sP to cover the item costs unless they're the weekend quest

...so tl;dr it's pretty normal

Thanks so much for the answer! Can you tell me where to find the Mage?

the mage can be found in shadowglen, in the little stone house at the base of the hill on the left side of the map.

He's here, or in Shadowglen if you're looking on the map :)

Last I heard, it was something like a 1 in 6 chance of getting a tome from him, though it's been a while so that may not be perfectly accurate these days (not The Worst chances, but not from every other amulet or anything, in other words)

Thank you!

Just wanted to say thanks from me too. I never knew about the Mage until I saw post. <3

One in six to one in seven is my own experience. The resulting Tomes from turning into the NPC Element Mage sell for seven times what the Mage Amulets sell for on the open market.

If your goal is quick sP selling the Mage Amulets will get you them sooner and be more sure. If your goal is training your pets or making them smarter, then go for the Tomes. Otherwise YMMV.

NPC Quentin is not the only quest grantor that doesn't tend to give you sP 'worth' that their required items cost. NPC Alexander's quest also does this. In this case he gives out items of high rarity and/or sP value.

All quests have a chance at dropping a Morty Card and IMO you will get two per day if you do them all. If you sell them or sell the resulting CSC from using them this averages our to an equivalent bonus of 50,000 sP per quest over and above whatever the quest grantor gives you. For this chance alone you should do Quentin anyway.