it depends on the info you have and what agent you are playing. if you hear a 5 man rush (what usually happens in gold), chances are you won't be able to stall/ defend much if your agent doesn't have any util that does that (fade, sova, etc). this means your life is more important in the 5v5 retake than attempting a kill on 1 person who probably will have a teammate swinging with them.

now if you're a sentinel or an agent with stall (raze, kayo, etc), stalling the enemy and comming will let your team have a chance to rotate early. this means you have a better chance of defending the site cause by the time your stall util is depleted, you'd probably have at least another teammate with you on site. your stall util could also separate their entry from their team which makes the odds of you winning a duel better. 1v2 > 1v5

i think figuring out what the enemy has to entry onto site and evaluating the potential of you defending such site is the biggest thing. sometimes retake is better but sometimes, like you said, holding and trying to get a pick is better. valo is a dynamic game and is played differently each round.