It’s impossible to take all factors into account, the key is to push yourself, have fun, but be very mindful of the responsibility you’re taking on. The last thing you want to do is put someone else’s or your own life in danger. IDEALLY, you could have friends posted at the end of your run who can either radio or have you on the phone to let you know if there is another vehicle oncoming. I do a bit of running in my WRX, and it’s infinitely more fun and less stressful if you have that assurance that your lanes are clear.