Ответ 1
Цикл массива # (бесконечный перечислитель) хорош для этого:
counselors = %w(C1 C2 C3).cycle
enquiries = Array.new(5){|i| "Enquiry #{(i+1).to_s}"}
enquiries.each{|enq| puts "Do something with #{enq} and #{counselors.next}."}
Выход
Do something with Enquiry 1 and C1.
Do something with Enquiry 2 and C2.
Do something with Enquiry 3 and C3.
Do something with Enquiry 4 and C1.
Do something with Enquiry 5 and C2.