12" LP @ 33 1/3 RPM - 14-18 minutes per side will give you a great sounding cut. Leading up to and over 20 minutes level starts to drop, surface noise will be more noticeable and bass might need to be trimmed. Sides over 24 minutes are possible but start to demonstrate the adjustments more noticeably.
12" LP @ 45 RPM - 12 minutes per side is optimal. For sides over 15 minutes, changing to 33 1/3 RPM might make sense.
Artwork guidelines summary:
Details on artwork submission are included on each artwork design template, plus we encourage you to read or provide your graphic designer our artwork guidelines.