Ok, the question is, Vette has the bonus to crit on treasure hunting, so there's no point on sending Quinn out to treasure hunt, because he doesn't have that bonus, correct?
If the efficiency bonus applies to time to complete, why doesn't it show Jeasa's time to complete an archaeology run as less than the other companions?
For gathering crew skills I would still send my other companions. But for crafting (advanced/superior/blues/purples/augment slot) don't waste resources by using an companion who has not a crit bonus in it.
BTW I think it should be mentioned that the chance to crit is based on your current crew skill. At least for gathering crew skills (diplomacy, scavenging, etc.) the difficulty of a mission and thus your change to crit as the amount of mats returned is based on your current crew skill.
For example you do a diplomacy mission with a crew skill of 10. On success it will only return 1-2 mats. Do the same mission with a crew skill of 85(the mission now show up in gray) and will return for example 16 mats. Plus there is a fair change to crit and gather purple mats as well. Please note that gray missions won't increase your crew skill.
I assume for crafting a higher crew skill increase your change to crit as well.
The big tip here is not to do mission with the actual intend to gather resources, but instead focusing on maximizing your crew skill as fast and cheap as possible.
Once you crew skill become so high that missions become gray a single mission can yield more in return than doing 10 mission when it was still yellow.