For what it's worth, I was told to avoid excessive stop work after I started having trouble with finger pain and numbness, so I don't do double-stop studies until my left hand and wrist are arching easily after a long warmup (hour or more). I have a heavily-rotated Russian-style hold, so I don't know how much good my bow-practice recommendations would do you (beyond "Paganini is evil," but I imagine you're already avoiding those right now).

I still drag out Hrimaly and Wohlfahrt every practice. (also doflein shifting studies... even the beginner ones... shh, don't tell!)

Have you tried Fiorelli? Even a very short session can be very productive for finger reach and wrist strength on the left hand, with plenty of interesting fingering. Little more bang for your buck with short practices because they're less obviously focused on one technique at a time and more lyrical, nice and smooth at times. I like to go light on the more-tiring Kreutzer, but _technically_ I alternate the two for technique building.