Are your axles made by Dexter? If so, here's a link to a Dexter service manual. It has lots of information about trailer brakes, including their recommended adjustment procedure: Dexter Service Manual
. The adjustment procedure starts on page 13.
Trailer brakes that are not self-adjusting do require periodic adjustment; as the brake shoes wear, the stopping capability is gradually reduced; it's so gradual it can catch you unaware. Adjusting brakes is not hard but the most important thing is to make sure your trailer is properly supported when you do it so it does not fall on you.
Also, the adjustment of your brake controller plays a vital part in braking safety.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch