If you are using an AW3 (the old type that most bikes had) then yes you will need to be bang on or it will go into neutral when you try and give it some welly. If you go for the newer and much improved SRF 3 then it's more likely to go into the gear to either side.
Cable tension is all important. What you could do as a proof of concept is get an old 3 speed trigger for peanuts/free and use that.
If you are using an AW3 (the old type that most bikes had) then yes you will need to be bang on or it will go into neutral when you try and give it some welly. If you go for the newer and much improved SRF 3 then it's more likely to go into the gear to either side.
Cable tension is all important. What you could do as a proof of concept is get an old 3 speed trigger for peanuts/free and use that.