That's not an easy answer for me because it would depend on both the type of hunting and the area. Then as a new machine is added, I tend to spend some time with that machine, and the time spent is somewhat determined if I like it or not after the first few hunts. Another factor is time, if I go for a short hunt then a grab and go beep and dig gets me started and going. Longer hunts like relic (I usually start with the Tejon) I get started and make fine adjustment more so at the beginning till I get it set for conditions and the types of finds.
So there are several variable involved and overall, I spend more time on general local hunts since it's close, convenient, and less time restricted. Relics hunts are more of a drive and takes more planning and time.
Then there is the unknown twilight zone variable - my mood.
Another variable is when my son or a newbie, or friend tags along who don't have a machine. I always let them take first choice so I'm left with one or two choices depending how many machines I take.
Enough boring babble yap at the lips (keyboard) - so I'll list and maybe add a comment or two.
Tesoro Compadre (New and works better than expected. Keeps impressing me in the trashy areas and is fun to use.)
Tesoro Silver uMax (Bought before the Compadre. My Fun Factor machine. Just like it but still getting used to it. Will pair up nice with the Compadre).
Tesoro Tejon (My first grab for relic. Deep and powerful. Doesn't wear me out swinging, does sometimes digging. Have used it effectively coin hunting too).
Tesoro Cibola (My first Cibola. Just used it some the other day, keep grabbing here and there. Already like an old friend that served well. Fast for local coin hunts)
Tesoro Cortes (I like the audio and smoothness. Bought because the sum mode caught my interest but I ended up hunting by audio, like my other Tesoro's)
Minelab Explorer-2 (Slow but sucks silver deep. Wears me out. It's my oldest now (sold everything else) so like an old friend I take once in awhile).
Fisher F-75 (Fairly new, not used to it yet. It is deep, fast and able to swing all day. I need to work with the audio as I'm not used to it - yet. Need more time)
Garrett ACE 250 (Actually bought for the wife. She didn't use it. Now a loaner mainly as It's a newbie most picked machine. I use once in awhile for ops check)
They order they are listed is because of particular reasons, like the Compadre being the newest machine, to the ACE 250 was not intended for myself. As I learn here and there and the spring weather breaks for relic, the order may be changed in a month or so. Then there are other factors such as the F-75 - need to work it more. Large coil works good. Small coil went bad and is being replaced.
Also, whenever I get a new coil, I tend to spend some dedicated time using it at first with which ever machine(s) it goes on.
In the last year - spent more time with Tesoro. Like the audio, response speed and weight. Guess that's why there five now.
Time before - used a Whites for many years and also did nugget shooting with a hand full of gold machines. Went through a number of other machines also.
What happened - I went through a phase where i wanted to replace all my older machines with the latest technology. There are a few machines now I wish I would have kept. It's too late now, like loosing a few old friends.
Currently - Still trying to figure what machines I want to keep, what to get rid of, and what I might want to add. Also not sure if I want to get back into the occasional gold nugget hunting. Gold nugget hunting took allot of patience, but I'm missing the hunt every time we get a good winter wash.
Future - I'm still lingering in the twilight zone