One popular non-standard configuration is RAID 10, which typically consists of two RAID 1 groups for data redundancy which are then used to create RAID 0 for improved performance.
There are many RAID users who need to recover data from RAID 0 arrays, which provide no data redundancy whatsoever. Such recovery attempts can be tricky, to say the least, because a single failed hard drive can be enough for critical bits of data to be lost forever. Your data recovery chances are much higher when performing data recovery on RAID 5 and RAID 1 arrays, for example, because of their baked-in data redundancy.
Just like when trying to solve any other data loss problem, time is an important factor when recovering files from RAID arrays. The sooner you begin the recovery process, the lower the chance of accidentally overwriting the lost files will be. Of course, you also need to use reliable RAID recovery software, such as Disk Drill.