Best of times

What do these ones mean? I'm confused with 'best of times' especially when 'times' is plural.

1. A perfect placement is difficult at the best of times.

2. Perfect placements is difficult at the best of times.

"At the best of times" usually means something like "in the best circumstances or situation possible."

I think the firs

Either then 'placements' being plural for #2, what is the dfiference in meaning between these two? Does it matter which one I say? They seem to have the same meaning?

1. A perfect placement is difficult at the best of times.

2. Perfect placements are difficult at the best of times.

Thanks.

They carry the same meaning without a context. Number 1 is a bit more 'pointed', i.e., would tend to be said for a specific incident. Number 2 might be said in a given incident, too, if the point of saying it was to characterize the incident as a general type of incident.