I’ve tried both ways and found that Lightroom runs best on the startup drive. Leave your files on an external drive. Creat Smart Previews on import, then use your MacBook wherever, couch, bed, etc. Plug in your external drive to export full size files. Or just export the Smart Previews for web use.
You can leave them on the external hard drive which I guess you use to save space on your computer. If you use a laptop you might want to create smart previews on import then you can edit them without the external hard drive connected. When you export, you can export from the smart previews which will give you small images good enough for web display. Or if you want full resolution, export when connected to your external hard drive.
I have an idea I haven’t tried yet. A 13” MacBook Pro with screen mirroring to an iPad used with a stylus. My eyes and back aren’t what they used to be, I can sit in a comfy chair with the iPad in hand, and then use a stylus as in input device, way superior to a mouse and maybe more intuitive than a Wacom tablet. Has anyone tried this?
I have been told by the security staff at Lincoln Center in NYC that photography is not allowed there although the the space is public and open. Does anyone know if this is true?
If you’re on a Wifi network, with the EOS6D2 you can use the Canon Connect app on an iPad, iPhone or android phone. Not only as a shutter release but also as a live view monitor.