Can a Christian get through a normal week without encountering immoral people?
No. Scripture teaches believers cannot avoid immoral people while living in this world. Paul explains that avoiding fornicators, covetous, extortioners, and idolaters altogether would require going out of the world, because such people are part of ordinary society and daily contact.
Les explains that Paul was addressing the Corinthians in response to a letter asking how they were supposed to deal with these things. By Holy Spirit inspiration, Paul was unloading. The problems in Corinth in A.D. 60 are still the same, because the human race doesn't change; churches and personal lives still have the same problems. Paul wrote not to company or have fellowship with fornicators or immoral people, yet not altogether with the fornicators of this world, the covetous, extortioners, or idolaters, for then must ye need go out of this world. Les says if you were to go through a whole week of life and never rub elbows with someone immoral or in gross sin, you'd have to leave this world because it's impossible. Even in Oklahoma and the Bible Belt, it is no different than any place else. Those who work in large office complexes or production facilities rub elbows with every one of these classes of people.
Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world.