I'm currently creating a new Journey in Journey Builder, in a similar way to an existing Journey we have, which was set up last year by a consultant we were working with. I've built many Journeys since, but they've all been very simple ones delivering a handful of emails to one data extension full of people.
This journey's data extension contains a few essential fields - email_address, firstname etc, but a lot of the attributes I'll need are in the parent data extension (from which this one is created via a query).
For a previous journey, a Population was set up, which allowed me to link the journey DE in an attribute set to the master one in the population. However we've now set up 3 different populations for different journeys for different audiences, each with their own population.
I have read that you should not set up more than three populations - so what am I supposed to do for new journeys? I must confess I don't fully understand the function of populations - and I'm not sure I understand attribute groups either.
I suppose my question is - can I set up a journey which sends emails which require data from fields in a separate data extension, using the Lookup Ampscript function, and what are the limitations of doing this?