Matthew J. Ruff Juvenile Law Blog on Lawyers.com

Yes.  In California, juveniles have the right to a speedy adjudication.
If the minor is detained, he or she has a right to a trial within 15 court days.  If the child is out of custody, he or she has a right to a speedy adjudication within 30 calender days.  Generally it is the child's attorney who has to make the determination as to what he or she has to do before proceeding with an adjudication of the juvenile case. The Juvenile Defense Lawyer needs to determine how much investigation
is required in the case and whether a psychological assessment of the minor is needed.  If the Juvenile Defense Attorney needs to conduct substantial investigation in the case, the minors counsel will ask that the child waive time to another court date. 

Problems occur when there are multitple co-minors on the same case.
There can be conflicting juvenile rights where one minor is asking for additional time and the co-minor is objecting and demanding a speedy adjudication.  When such a scenario comes up, the Juvenile Courts are governed by Welfare and Institutions Code section 700 which states that, the Juvenile Court shall continue the hearing not to exceed seven days to make an appointment of counsel, or to enable the juvenile
lawyer to acquaint himself or herself with the case.  (See also AA. v.
Superior Court, (2003), 115 Cal.App.4th 1.)  As a practical matter, if
you are a private juvenile defense counsel substituting in a case
involving multiple co-minors, its a good idea to convince the other
co-minors attorneys to waive time otherwise you will only have a short
time window to acquaint yourself with the case.

It should be noted that a juvenile cannot challenge the denial of his
speedy trial after he or she has admitted the allegations.  (Ricki J.
V. Superior Court (2005) 128 Cal.App.4th.783).

Even if there is a speedy trial right violated, the minor must show the
error amounted to a miscarriage of justice to reverse the
jurisdisdicitonal order.  In the case of In re Chung D. (2006) 135
Cal.App.4th 1303, the juvenile court had granted the prosecutor's
request for an eight day recess in the middle of the adjudication.  The
California Court of Appeals ruled that the child's right to a speedy
trial right was violated but upheld the sustained petition because  the
child was unable to establish that the error amounted to a miscarriage
of justice.  The minor must show prejudice under Welfare and
Instituions Code section 782 before a court can dismiss the case with
prejudice.  (Derek L. C. Superior Court (1982) 137 Cal.App.3d 228).

If the Juvenile prosecutor is unable to proceed on the last day set for
adjudication and there is no good cause for a continuance, the juvenile
must be released from custody.  If the Juvenile refiles the dismissed
petition, the child is still to remain out of custody.  This is
important to remember because it is not uncommon for a Juvenile
Prosecutor to dismiss and refile a case when the Juvenile DA is unable
to secure an important witness.  If your child is facing a juvenile
case, you should consult with an experienced Juvenile Lawyer that is
familiar with the Juvenile Court Procedures.  It is important to know
the Welfare and Institutions Code inside and out as well as be well
versed with all the published California Juvenile Appellate cases.
Children deserve the best juvenile defense.