Tierod spacer question

[NJs13_1993]

When installing a bolt on spacer on one side and a slip on on the other is the only time the rack needs to be centered right? And when centering the rack do you have to take the steering shaft off it can you just center it by removing the steering wheel and recentering it there?

Or do you guys recommend one slip on spacer on each side instead of the bolt on and slip on?

Thanks for the help