Here are the videos. Anyone here interested in growing lettuce should watch them. As you can see these people are using them as recommended by manufacturer. I had a Philips Horti specialist help me design my system. He sent me ppfd charts specifically for my layout and provided guidance on how to use the bars. if you get in touch with them they will help you understand how to use them properly to get the results you want. You'd also learn some specific science stuff behind how they intend them to be used. - part of their sales process is to work with the horti specialist to ensure you system design is correctly matching the design of the bars for optimal results.
It's not up to that lettuce lady to teach you how to use a product, she's got her own business to run. I'm going to do a side by side comparison between four t5 and 2 Philips bars and see.