There's lots of reasons why you should follow the Toyota workshop manual (not Toyota dealerships) on this.
In regard to replacing fuel pipes.
New injectors = new pipes.
You can re-use them on the same Injectors, if they are clean, up to 3 times in total. But be very carefull.
Baileys has done some r&d on this as have I, we agree on the 3 times thing.
However I'm a little more strict, I really don't want to re-use your pipes with new or replacement like new injectors.
My biggest reason is:
You are spending a lot of money, new Injectors & all the other parts & labour, why take the risk?
What risk you ask?
Have a look at all the sh!t that falls off the dirty, corroded bastsrd$.
It can be hard to see in the pics, but lots of crud.
This engine was a bit of a pig, it was degreaser & truck washed before the job, but the stain stays.
As does the sh!t in around the nozzle holder seals & pipes.
DO YOU WANT THOSE DIRTY PIPES NEAR YOUR BRAND NEW INJECTORS?
Before you answer I will remind you, there are 8 tiny holes in the end of the fuel injectors, smaller than a hair, you cannot see them with you eye, also very tight tolerances inside.
I can see the crap & corrosion on the pipes, do you think it may cause a problem if its going through your Injectors & jammed in a hole?
Mess up your spray pattern? Well who knows, keep your answer to yourself
This is likely another reason so many people getting the customer service exercise done are getting the vehicles back with problems.
How much care are they taking? Could you be so carefull to not get crap in the new Or even used injectors? IMO no, I'm not confident.
Do we need more reasons?
After years of 22,000psi, erosion may be taking place inside the pipes, there may be particles that could make it to your injectors.
Each time you use the pipes, they squash, IMO overusing is risking leaks that may start at a later date.
Don't forget they must be torqued.
32nm for new.
35nm for re-using.
Just hope the last guy didn't crank them with the spanner to about 40-50 nm.