The original papers I have seen with a number of 10 up to 50 hp. electric motors, have noted a grease type, and a grease amount in weight, to be added every so many hours of operating time. In hand with this is often the instruction to remove the zerk or other plug, after greasing, operate motor until at temputure, for a time period. This would allow excess grease to leave and not burst a seal.
As not many have motor documents, it can be a crap shoot. Lots of different types of grease, lots of manufactors, lots of, this is better then this. Could sound like an oil post!
My father said he worked at an old mine once, he went to the boss one day saying they had no grease for the ore cart wheel bearings, and dam near couldn't move them! Boss said to use canned butter, they had lots of that!
Over greasing as well under greasing can cause temputure problems. A number of times I have taken bearings out of old equipment, the bearing has only the soap base left in it and no oil, nearly hard as dried mud, fresh grease would not help much.
A bearing seminar I went to, did say, manufacters recommend a grease based on operating rpm, heat, loading, projected use, grease type for corrosion and ball/roller/race fatigue/failure resistance and seal compatability, if used, and availability. So little bearings are one thing, but when you need more then one crane to even move the bearing, you don't mess around. If the bearing is supporting people, you don't mess around.
Some lube is better then no lube, some lube is better then to much lube, the rite lube "may" make a difference.