[Fot] engaging/disengaging the overdrive?

[Scott Janzen]

all this talk about overdrives made me realize I don't know the proper way to
use one - I am taking the TR4 to the Turkey Bowl at Summit Point this weekend
(supposed to be dry but cold) and this year, the overdrive is working - last
year it wasn't (loose connection - easy fix).  So, it's the first time I've
actually driven a car with overdrive, as none of my previous LBCs or BBCs have
had one.

Do I:
- keep my foot to the floor on the upshift
- momentarily lift
and on the downshift:
 - keep the revs up
 - turn the OD off at the same time as downshifting for the turn while the
clutch is depressed?

I'm assuming I can stay in OD and shift between 3rd and 4th normally?

I'm looking for both the "preserve the unit" answer and the "what can I get
away with and for how long" during racing answer.