I've tried quite a few over the years, often from necessity because that what the local shop had. I haven’t had quite the same experience with drying times as you -but it’s subjective:
- Humbrol -awful, thin as water or a hard paste. Takes an age to dry, really poor consistency. Just awful stuff!
- Revell -skins too quick which slows down curing then stays a soft blob for days no matter how thick. Eventually dries very, very hard which makes sanding difficult, and it's subject to cracking. Terrible stuff but not quite as bad as Humbrol!
- Deluxe solvent free "perfect plastic putty" -recommended to me by local shop out here in Paris. OK suppose: dries quick, no smell, water clean-up if that's important, doesn’t stick too well to polystyrene unless you're filling a crack or crevice (no surprise). It’s “meh” but useable but I don’t recommend it for polystyrene unless it’s a delicate airfix type kit, plastic needs scoring or hard sanding for it to stick unlike solvent types which need less prep. I suspect it’s just DIY white “decorators caulk” re-tubed and at a massively inflated price (smells, feels, looks and sands the same). 7/10 I’m always left a bit wanting with Deluxe products, this is no different -like Apple: clever marketing for "so-so" performance
- Testors putty -recommended to me out here in Paris, never tried it until February. Solvent based -nice to apply, easy to work with, dries quick, sands easy. Not bad at all, really quite good
- Squadron putty (red) - solvent based, sticks excellent, dries quick, easy to work with, very easy to sand. Consistently the best of anything I’ve had. My No 1 choice for wood or plastic, period. I buy 2 tubes each time. If shops don’t have any I resort to E-Bay -it’s worth the rip-off courier shipping costs because of the solvent, RM won't deliver it
...Could of course try making your own with those last few dregs of MEK or a squidge of Contacta professional liquid poly when the tube blocks. Done it a few times. Don't use polystyrene dust from sanding -it always seems to have bits of abrasive in it, just plop some small offcuts in the liquid and seal it up intil it turns to goo. Mixed results for me really. The solvent can stay active for absolutely ages and sometimes distorts the joint long afterwards.
Depending how big the job, 2K Isopon plastic car bumper repair putty from motor factors or Halfords is great and works well with polystyrene and sands very nicely (wet). Dries a bit flexible also. Great on Polystyrene and GRP. Stinks though because it's polyester based (or uses the same red hardener anyway). Really like it, much prefer it to Milliput or epoxy putty, and you can start sanding back super quick.
...Sorry for the brain dump -might give some ideas.
Rich