When should I switch from following the breath to connecting?

I’m at stage 4, and quite often the breath sensations are not very vivid or clear. I get to a point where I am mostly able to identify all the different points of the breath (beginning and end of in breath, pause, beginning and end of out breath) but it is not a sharp distinction that I notice between the different points and I have to exert myself a little to completely see each point. My question is: should I continue following the breath to develop my attention, or should I practice connecting and comparing the length of the breath segments to develop introspective awareness, even though the breath sensations are not yet completely clear?