Bearings from different manufacturers may vary in perceived or actual quality. However, using only a handful bearings, may not indicate which firm on average is better. The load capacity of bearings is based on statistic tests carried out out on a very large number of bearings and dates back to work carried out in the late forties of the previous age. Since then the method for calculating the acceptable loads has been redesigned somewhat in the sense that bearing alignment and quality lubrication also are part of the calculation. The result however, still is based on statistics. That means that when you apply a certain load to a bearing in actual use a small number of the bearings will still fail prematurely, most of them will reach the number of revolutions that may reasonably be expected and some will last much longer....

Over the years both the materials used in bearings and the way they are machined have improved, resulting in higher acceptable loads, as reflected in the proprietary load calculating methods of some of the larger bearing manufacturers. Those adaptations more or less reflect the quality improvements resulting from better materials. Whether that will be visible in actual operating life can only be demonstrated statistically - and a single application will not yield reliable data...

A more practical approach might be looking into the risks that premature failure would bring about. Can the bearing be easily exchanged, will failure cause harm to people, will failure cause high costs in terms of production loss or loss of customers? In quite a lot of cases the cost of more costly bearings will then be not that important.

Low speed application together with occasional shock loading is not the type of loading roller bearings prefer. Neither is occasional use. Those might well be the conditions where more expensive bearings can cope with better then cheap ones.

Two bearings that carry the same basic designation (for instance a 6205 ball bearing) but are not from the same manufacturer are guaranteed to be of the same basic type and to follow ISO standards for outside dimensions (inner diameter, outside diameter, width).

That's all that is guaranteed.

When it comes to internal design of the bearing (number of balls, size of balls, thickness of rings, conformity (ratio of ball curvature to raceway curvature), surface roughness, heat treatment, steel cleanliness, quality control - all this will all affect the performance of the bearing.

In general, with a higher end bearing, you can expect:
- Cleaner steel with less inclusions (reduces the risk of subsurface initiated fatigue earlier in the life of the bearing)
- Better heat treatment that will improve the life of the bearing by improving one or several characteristics:: crack resistance, crack propagation resistance, shock load resistance, wear resistance
- More sturdy cage design (for example the rivets holding the sections together are more sturdy, or the cage's general construction is tougher at the right places)
- Better cage pocket topography (that is the design of the surface of the cage pocket here the ball or roller comes in contact with the cage - a higher quality bearing will have an optimized design that will reduce wear, friction, operating temperature
- Optimized conformity (ratio of ball curvature to raceway curvature)
- Higher quality grease (for bearings which are sealed for life)

With respect to your application, if the speed is below 10 RPM (considered static) and the load will not surpass 50% of the static load rating of the bearing, I would say cheap bearings would be sufficient, however it depends on how critical this application is and how easy it is to change out the bearing in the case of a failure.

Their materials, processing technology.、
There are many differences in accuracy.

Supply Forever Global Industry Co., Ltd.
https://www.supplyforever.com/

A more practical approach might be to study the risks of premature failures. Whether the bearing can be easily replaced, whether the fault will cause harm to people, and the failure will lead to production loss or high cost of customer loss? In many cases, the cost of more expensive bearings will not be as important.

Supply Forever Global Industry Co., Ltd.
https://www.supplyforever.com/