The typical length of a lesson can last up to 50-60 minutes.
The teaching methods I use involve teaching the student on the topics they are struggling with, then letting them practise the topic with some questions. After the questions I will go through the answers and correct any mistakes during this time, and give help if needed during the answering of questions.
My lessons are for GCSE and A level maths students and A level chemistry students specifically for organic chemistry.