Is it better to run one large load or multiple small loads to extend life of bearing?
Bearings tend to wear out as a result of repeated cyclical loads.  As a rule of thumb, based on fatigue failure of metals:

The damage done by a single cycle of a load is proportional to the load raised to the power of 3 or 3.3.  When the total of the damage done reaches some threshold, the part will fail.  The threshold cannot quite be predicted in advance.  For example:


If a bearing can handle 1,000,000 cycles of a 5 pound-force load, it can handle
100,000 cycles of a 10 pound-force load, or
50,000 cycles of a 10 pound-force load plus 500,000 cycles of a 5 pound-force load, or
10,000 cycles of a 20 pound-force load, or
1,000 cycles of an 40 pound-force load, or
250,000 cycles of a 5 pound-force load, 25,000 cycles of a 10 pound-force load, 2,500 cycles of a 20 pound-force load, and 250 cycles of a 40 pound-force load.


Each time the bearing turns while subject to an eccentric load counts as a "cycle".  Thus, washing one load of clothes can cause hundreds of cycles of damage to the bearings.

The Timken Engineering Manual has more details.