letrozole as extended hormone treatment

I am interested to know if many people are taking letrozole (femara) for a further 5 years after tamoxifen to reduce risk of recurrence? Is it more likely to be given in younger people? Is it just given like this in trials? I have had tamoxifen for a year and then a gap and then anastrozole for about 3 1/2 years and the plan is to stop these now have nearly reached 5 years from starting hormone . It doesn’t seem much compared with 5 years tamoxifen and then 5 years letrozole.