In another perspective, the instant kill feature meant to complete daily/weekly/monthly mission quicker (those with darting individual creatures).
The perfect hit grants you max DNA/dart, while the insta-kill feature complete the darting session for the landed 1 dart.
I have tested the features, basically you can get max DNA/creature if you have fired 15 darts, and use insta-kill + perfect hit feature on the 15th dart. (not time related but dart count from beginning of dart session - end of dart session).
While fast supply spin feature actually give you full supply spin reward (not the discounted reward if you're at distant) within 300m range (some further Spin wont be able to spin, so yeah.. My guess within 300m range).
Thats my 2 cents on the newly added features.
@AlyssaX64 May I know if there is any chance to include the speed manager in the next update? 😅