Which workout should I drop?

I’m going to have to drop a workout this week. I’m on the Olympic tri medium volume base phase. I have shasta tonight (60 min aerobic with sprints) and galena on Sunday (90 min 3 x 20sweetspot). I was going to drop shasta as it seems less specific to the Olympic tri requirements but is there something I don’t know about the effectiveness of these sprints over the longer sweetspot session?

Your thinking is correct, dropping the more aerobic and less specific workouts are the best way to go. You will get the most bang for your buck out of the sweet spot intervals. The only caveat would be if you’re feeling particularly fatigued and could use some extra recovery, then I would do the opposite.