Rules to reduce interval times?, Anything in the RAW? Options

[Faradon]

Are there any rules in SR4 for reducing interval times? (and let me preface by saying I am not an expert with SR4 rules... so cut me some slack please)

Teamwork just seems to add dice to the main person's pool from a helper.
- Auto Mechanic and Assistant... assistant rolls 2 hits and gives 2 dice to Mechanic for his roll to supercharge a car.

Scenario 1:
A classic car has been disassembled and smuggled across the border.
Ten mechanics are waiting in a garage to reassemble it.
Reassembling a car is given a Threshold 10, 1 Week interval.
By the teamwork rule as written each mechanic would roll and add successes to one main person... still taking the full week and having a really crappy return on investment for hiring 10 mechanics.

Multiple initiative passes seem to be completely ignored as well...
-Hacker A and B have the same Skill+Attribute.
-Hacker A is programming AR and has 1 Pass...
-Hacker B is programming in Hot Sim VR with a Simsense Booster and a Sleep Regulator with 4 Passes...
-After a 1 week interval test they both just roll 1 dice pool

Am I missing something?
In Scenerio 1 why can't you "buy down" the interval with extra skilled help? (pay money / more people to reduce interval rolls)
In scenario 2 why do no factors ever apply to how long the interval tests are? (Risk some VR addiction/burnout... cut some time?)