I used to live on caffeine. 200mgs - 3 to 4 X/day. E at 25mg - 3 to 4 X/day. Years ago I'd use Yohimbine at 10mgs - 3 x or more a day with the above. I do prefer Alpha-Y over Y.
Now I've have very little tolerance for caffeine. I'll get benign PVCs (premature ventral contractions) once my heart rate increases during exercise. I can have 1,3 and A-Y alone but add caffeine to either and I get symptomatic. Cardiologist gives my a clean bill of health with perfectly normal valves and structure
I recently stated using A-Y fasted cardio and for some reason I'm sensitive to the irritability and mild anxiety - clammy sweats and chills.
Therefore I stick with my premade (pump/endurance/stamina) preworkout that are free from caffeine and Yohimbine and 1,3. This allows me to increase my dose as desired without increased stimulants. I add them selectively and in controlled doses.
Yesterday I saw a decent preworkout formula and I was tempted to put my name into the contest but saw that a single serving had 450mgs of caffeine. The other pump/endurance/stamina ingredients were lower doses than my usual intake but the 450mgs caffeine made it impossible to 1.5-2X dose it. That's just stupid IMHO.
To answer the question - I keep it out of my preworkout formula.