I have a print that will take about 40 hours to complete. Is it ok to run the printer for that long straight? Is there anything I should do/take into consideration before I embark on what could be a lot of filament waste. 
Thanks!
I have run a number of 2+ day prints, but when you run that long you need to make sure you prevent sudden air cooling. I keep my Taz 6 in a small closet(6’x6’) that I keep the door closed on and it has printed great for several months now even ABS.
You might want to be printing off the SD card for something that size.