If you are claiming contributions based it only lasts 6 months and if you have over £16,000 in savings you are entitled to nothing any thing under then you go on jsa at a reduced rate if you have savings over £6000.
You are right about it only lasting 6 months but you are wrong about the savings part. It doesnt matter how much money you have in savings as contributions based JSA is given if you have paid in class 1 NI for 2 years or over. Income based JSA takes into consideration savings, whether your partner works etc.