OP, definitely no more than 3 hours for both rear shocks, shock mounts, and brake rotors and pads, and springpads all together. I just did one of mine and tracked the time. Still takes max 90 minutes even though the rear seat might have to be accessed.
You should definitely do the rear shock mounts if you also do the shocks, and you should definitely get Meyle HD. Leave the brake rotors and pads to some other time if you have at least 1 year left on them. The workshopwill be able to estimate this just by looking at it. So bid for 3 hours flat of labour when you go down to negotiate, and bring your own parts, or quote them prices of the parts you see online (together with shipping) and insist on them matching it.
Be aggressive in your negotiations if you need to, since you now know how much time is required. Refer to a vague "the other workshop" that wanted to charge your both arms and 1 leg and you are having none of it, etc etc.
It would be a good idea for you to purchase and change the water pump and thermostat at the same session if you have not already done that, to minimise your downtime. I know that adds to your costs significantly but see you're protecting your engine and preventing further exorbitant costs. Remember, your engine is fragile and will blow up if the temp only hits 3/4 lolol. Just kidding. Consider doing other things to maximise the value of this downtime.