There are actually a number of ways to switch anti-depressants & I’m sure her GP/MH team weighed up the pros/cons. A direct switch isn’t always the best option as you have mentioned.I also found it interesting that her GP made her wean off her Citalopram before going onto Venlafaxine as the guidelines say to stop taking your short-acting SSRI (which is what Citalopram is) and start taking the Venlafaxine the next day. Maybe her whole mental breakdown could have been avoided
It sounds like she has had a conservative/moderate switch (not sure as don’t really listen to MFM’s dribble). Or you can do a cross-taper switch.
If you are going from one SSRI to another then a direct switch might be a good option. But she’s gone from SSRI (cit) to a SNRI (ven). Anyway switching drugs can be a long and horrible process especially if you’ve been on them long term. I feel for anyone who ever has to go through it!