I use nm L/R in cruise and headings on climb descent when on approach/departures.
I teach guys to ask for more miles than they need as many ask for not enough/barely enough.
You can see the weather at 80nm but it is usually to early to make a decision until 40nm or even 20nm.
If I can't get a clearance I am going to divert around it anyway. Fortunately a clearance has always been forthcoming so I mustn't be leaving it to late to ask.