Spartan series
The day and night cycle within Perilith was not the same as the Primeveil, although it was close enough. Every day at exactly 5:30 am the sun would rise within Perilith, and at exactly 6:30 pm the sun would set, without any deviation whatsoever - at least so far. That provided a solid thirteen hours for the teams to thoroughly explore the alternate dimension.
There were certain drawbacks to having to return every night, however. Ultimately, there would only be a certain distance they could travel to and return within a 13 hour time frame. At the moment, spending the night within Perilith, even with a night light there to fight away the darkness, had not proven effective.
Perhaps, over the next few weeks, they would discover an alternative way to circumvent this issue. They surely had to if they were going to achieve the objective of retrieving all of the six Sage level ingredients. Most likely, that would involve bringing in more teams of Neophytes.