Generally if you have b factors over 150 the map is not suitable to build a good model, i.e. the map is not model buildable quality. It is possible but unlikely collecting more particles from this grid prep will decrease the b factor and you might benefit from making another sample with optimized ice/orientations.
The reason for this is because the map resolution scales linearly with log number of particles while the b factor sets the slope of the line (see image). Basically the higher the b factor, the slower the resolution will improve by incorporating more particles. Essentially at very high b-factors the map does not improve much by collecting more data and so grid optimization is probably best.
