Can I apply for naturalisation as a British citizen after 10 years of immigration compliance or after the 5 years qualifying period?
Both requirements apply. The 5-year period is more about proving your continuous residence throughout that time. The 10 year period is the maximum period up to which the lawfulness of residence will be checked. If someone has been resident in the UK for less than 10 years, they do not have to wait until they reach the 10-year mark. That is only the maximum period which will be assessed. Of course, someone who came to the UK 6 years ago, was lawful for 5 years, then received their settled status straight away and has waited one year, does not have to wait before applying to naturalise.