There are many factors which go into this calculation. The first one is the severity of the injuries as if you have severe injuries one must often wait one full year from the date of the accident before your medical doctors and other treating professionals are able to give a prognosis or an opinion about what the future holds for you.
Knowing the future is very important in assessing the value of the claim as obviously an injury with a permanent impairment rating is worth far more than an injury that is resolved after 10 months. As well the permanent injury will have long term future loss of wages to be claimed and future treatment costs to be claimed, as well as long term future housekeeping claims.
Having said all the above, the majority of the cases, even serious cases we take can be resolved within two to three years from the day of the claim because after one year we obtain all the detailed medical reports and then go to work on a settlement and/or litigation to bring about the resolution to your case.
Unfortunately, in Alberta, due to underfunding of the legal system, one of the biggest delays we encounter is simply getting a trial date as our Alberta courts are lacking in court room facilities, Judges, Court Clerks etc., so that getting a trial date often results in the longest delay.