Mmm, no. 'Pattern' is the long standing word used around the SPF to describe a super chest's drop seed. In other words, it's not random that the Ber Rune dropped along with a War Sword, Ring, and Wyrmhide Boots. That 'pattern' or 'seeded drop' has been the same since 1.13 went live in 2010.
Here's a link to the thread where people were originally figuring out what 'patterns' or 'seeded drops' were available once the rune drop rate got increased in 1.13. If you hit the spoiler tab at the bottom of the first post you'll see the 'patterns' listed for the P7 Vex and Ber Runes I pictured above plus all the other seeded drops that are possible for runes Pul and up at P3, P5, and P7. This is possible because what comes out of super chests isn't random, but rather one of 65,536 predetermined possibilities.
Now, with racks though, you are correct. Rack drops are influenced by the route you take to get to them and also monsters in the area ... and probably some other factors ...
... and since we're talking about racks ...
Most of the racks on my LK map are total bummers. But, I have this one armor rack that tends to drop Totemic Masks:
View attachment 69075
So far, I've gotten three Jalal's ...
But that's not what's exciting! When there are monsters in the area to 'spoil' the Totemic Mask drop, I often get Paladin shields! Here's my top drops so far:
Sacred Targe
Defense: 132
Chance to Block: 0
Durability: 26 of 45
Required Level: 47
Required Strength: 86
Fingerprint: 0xccbf756e
Item Level: 79
Version: Resurrected
All Resistances +43
Gilded Shield
Defense: 166
Chance to Block: 0
Durability: 29 of 50
Required Level: 38
Required Strength: 89
Fingerprint: 0xcbf2361c
Item Level: 79
Version: Resurrected
All Resistances +45
Akaran Targe
Defense: 118
Chance to Block: 0
Durability: 13 of 20
Required Level: 26
Required Strength: 44
Fingerprint: 0xf9ce1ccb
Item Level: 79
Version: Resurrected
All Resistances +44
Good Paladin shields can be so hard to find. So it was super nice to able to pick up some quality Spirit bases (both for endgame and for leveling) while looking for the runes for my future Hammerdin

. And who knows, with any luck, I may be able to come across a 45 resist all Sacred Targe before all is said and done

.