Good best practices for floodlights are:
1) you are using DV360 or SA360 and are generating an audience to target or exclude for future initiatives
2) it directly measures a KPI for the client
3) it's a landing page that we're driving media to
4) it's an action designated as a conversion
A lot of things can be measured by site analytics that don't need to be measured by a floodlight. Click to call? Click to email? newsletter signups? <--all of that can be measured on site analytics. Using the above 4 best practices will help you in making the floodlights and avoiding the headaches of getting them placed/validated
Floodlights are last touch attribution for PAID MEDIA served or tracked through the ad server. You will not see a customer journey with a floodlight. You will not get multitouch attribution with a floodlight. You'll need c3 for MTA. Customer journey can be tracked within the analytics tool.