(define (skip list n)
    (cond ((null? list) '())
          ((<= n 0) list)
          (else
              (skip (cdr list) (- n 1)))))

(define (splice list n m)
    (let loop ((stop (- m n)) (list (skip list n)))
        (if (or (eq? stop 0) (null? list))
            '()
            (cons (car list) (loop (- stop 1) (cdr list))))))

(define (group-for list count)
    (let ((step (/ (length list) count)))
        (let loop ((i 0))
            (if (eq? i count)
                '()
                (cons (splice list (* i count) (* (+ i 1) count)) 
                      (loop (+ i 1)))))))

Function group-for which return list of list of length n.
(group-for '(1 2 3 4 5 6 7 8 9) 3)
=> ((1 2 3) (4 5 6) (7 8 9))

Function split list to lists of length n.

Scheme