Hi Buggy, yes it all depends on circumstances. If the lift is in a sterile lobby then it should not make much difference if the doors at the base of the shaft are open, but if the lift descends into an area of fire risk, eg a shop sales floor then if the lift shaft connects two fire compartments there would be a problem, because as you are aware, doors into protected shaft only have half the fire resistance of the elements of structure, as a fire would have to break though two doors to breach the compartment. That safeguard would be negated if the lift doors were open.
Thats why I stated in the last post that lifts should only be interfaced to the fire alarm in certain circumstances. The consequences of being dumped into a blazing inferno of a shop sales floor with no way out doesn't bear thinking about.