Can a person manage 100 orders at a time?

[picvidpro]

I have seen some sellers having more that 100 orders at a time with 2 days delivery for a logo design! I have few questions!

1. Can he/she can able to manage designing 100s of logo at a time?
2. What if he/she use some other people to design? Is that allowed in fiverr?
3. And what might the trick they using to get such more orders? Are they kind of advertising their gig? Is that allowed in fiverr?