Far more bearings fail from over greasing than under. Grease is manufactured from oil and a "carrier". That carrier can be many things from wax to Lithium. They are cooked together so they with emulsify. When a bearing has too much grease, it will heat up. That heat separates the carrier from the lubricating oil, and the when the oil goes back to it's original liquid form, it runs out of the seals, leaving only the carrier, and the bearing fails.
In over 30 years as a Millwright/Machinist, I've replaced an uncountable number of bearings. There was "wax" left in nearly all of them.
Throw the bearing buddies away, or gift them to someone you despise.
The lips on a bearing seal are designed to let things out, but not let anything in, especially water. If the spindle rusts, it will take out the seal, let water, dirt, and all kinds of nasty contamination in. That will take out a bearing quick as well. A bad seal is...well...it's just bad.
The bearings on my boat trailer lasted from 1984 when the boat was new, until I replaced them this past summer. We only towed that 24' boat about 1600-2000 miles per year, but it adds up. A few minutes of maintenance goes a long way.