@threads :static divides the range into packs 1:n/nthreads, n/nthreads+1:2n/nthreads …
For example with four threads and a range divisible by four you get
julia> A = Vector{Int64}(undef, 16);
julia> Threads.@threads for i=1:16
A[i] = Threads.threadid();
end
julia> A
16-element Vector{Int64}:
1
1
1
1
2
2
2
2
3
3
3
3
4
4
4
4
If you want [1,5,9,13] to be scheduled on e.g. thread 1, you would need to do your own task wrapping and scheduling.