How much due dilligence?

[Emily Laughlin]

In a market where time is of the essence, how much due diligence should I be doing before an offer and after the offer during the allotted "due diligence" time? More than once now I have missed out on an opportunity because it is under contract before I am able to complete my analysis/research and get my offer in. 

Wondering how much analysis and research is sufficient to make an offer and what details/assessments are better saved for the due diligence stage?