7th PC Patterns
Let's assume that you are attempting consecutive 4-height PCs. Each 4-height PC requires 10 pieces, and each bag has 7 pieces. Therefore, you can complete a full loop on your 7th PC because 70 pieces (10 pieces × 7 PCs) are divisible by 7, a whole bag. This makes the 7th PC unique—the 7th PC being on the end of the loop means that it can be thought of 3 leftover pieces + 7 pieces from the 10th bag.
This page lists some patterns that you could use for your 7th PC. However, it is by no means comprehensive, i.e., it will not cover every possible 3 piece combination. If interested, a good supplementary page to look at could be knewjade's Best Chance Field.
Every pattern shown here has a 100% chance of PC.OST
See below for an alternate pattern that you can use for IJT
ILZ has a corresponding 100% pattern.