When do you normally finish precursors chains?

[Dustman]

For me it's usually late, in fifties or later, but luck plays big role:

 

[Kunae]

It's all down to luck.

 

[Dustman]

Yeah, getting two Archaeologists and one Archaeologist/Carefree really helped to grab anomalies before they got blocked by hostiles this time. Normally I need to go to war just to get access to couple of anomalies.

 

[bobucles]

Immediately, if it's not the first league.

 

[Mastikator]

The bigger the galaxy the faster and emptier I can get it done. If I run into the (common) situation where everyone closes their borders and all systems are explored then I generally have to wait 100 years or more.