Greasing bearings question

I recently had a bearing failure after a quick inspection 2 months earlier. I removed 2 of the 4 drums and found plenty of grease on the bearings but I didn't clean and fully examine the bearings. They had the original black grease in Lippert axles 5 years old. I replaced the bearings and brakes on the failed unit at a campsite and then inspected the other 3 more thoroughly when I got home. As it turns out 3 of the 4 were bad (galled rollers on the outer bearings). All new now with red grease #2. Just greasing from the zerk fitting will not reveal the true condition of the bearings. Also, you should not mix different types of grease. Do you know what is currently being used before adding your grease? Lippert apparently used a black grease and the new Dexter drum/bearing assembly came with red grease. That's my recent history; hope it helps someone to avoid a catastrophic failure. I don't know if it is relevant or not but my 3 prior trailers all had Dexter axles and zero failures. I've always done my own bearing maintenance over the past 21 years.