A tad long but stick with it.
There are similar questions on this forum around this subject but can I give a scenario and get the views of my learned fellow members.
I have 3 batteries all numbered, 1, 2, and 3. I always use batteries sequentially e.g 2, 3, 1, 2, 3, etc etc
I charge all batteries to full before going out and complete a flight with battery 2. I put battery 3 into the drone but am not able to fly.
I return home knowing that battery 2 requires charging, but knowing I hope to fly the next day, leave everything as-is.
The next day I am not able to fly so leave stuff again as-is.
Itās a week till iām able to fly but by this time batteries 1 and 3 have discharged to about 75% along with battery 2 still flat.
So, do I just charge batteries 3 and 1 (both 75%) back to full to allow me to fly sooner, get fully discharged and charge all together, 1, 2 and 3 or, charge 3 and 1 separately ?
I am aware that āCyclesā are an important factor in battery life although Iām not fully understanding if charging from 75% to full would count as a cycle and from what percentage would count as one.
Your views and advice would be helpful once again here folks.
Thank you
Mike
When I used to leave the drone in the car I always had one battery fully charged all the time, just in case. And always that same one battery.
Iād then only charge the remaining batteries if I knew for certain Iād be able to fly a few batteries worth of airtime on a given day.
This led me to having a single battery with a high charge count, a sacrificial battery almost, and a bunch of other batteries that were beautifully maintained.
That wonāt work for everyone but Iām throwing it in to the mix for discussion 
I would definitely charge the fully used battery when I get home. Leaving batteries fully discharged can be detrimental to battery life and their ability to hold a charge. The other 2 batteries I would leave until I know Im going flying again.
So, so, so many times Iāve hoped to get in a load of flying, charged all 4 batteries, and then never flown - that Iāve given up (over the 6+ years Iāve had my MP) worrying about which I do what with. And Iāve never bothered checking the number of recharges on each. They all will give me very close to original flying time - and in the end thatās all that I need to know.
And Iāve never bothered checking the number of recharges on each.
To me, minimising the recycles would mean thereās more chance of wanting to fly but the batteries wonāt be recharged in time. So - if Iām going out to fly, I recharge them all.
They all will give me very close to original flying time
Sometimes I have recharged all 4 - gone to a field on a sunny day and just sat there timing a hover until it gets to critical - so as to check the available flight time of each. So that will be another recycle thatās logged. 
Max flight time is the thing thatās often the most important factor for me ā¦ long range over the sea I want to know itās going to bring the drone back. Using a battery Iāve rarely used to keep recycles low is no use to me if I discover, during the flight, that itās no longer giving anticipated flight time.
There is one slightly scuffed battery that tends to live in the drone and hence is the first to be recharged. But thatās more because the other three have been wrapped and I want to keep the wrap un-scuffed. 
The āslightly scuffedā battery is 6 years 3 months old - the very first that I put in the MP when it arrived - and goodness knows how many flights/recycles itās done around Europe.
@PingSpike
I like the idea of a āsacrificialā battery.
@SirGunner
Duly noted your comment and it makes sense to me.
@OzoneVibe
Havenāt we all done that.
Food for thought but again makes sense.
To sum up, Iām over thinking this whole thingā¦Move on and fly.
Thanks all
No, your not over thinking. If you are I used to do the same thingš¤£.
All Iām really ly conserned with now is either really hammering a battery down below 15 percent or so, or not charging a battery thatās been discharged.
If Iām going out Iāll charge 4 or the 5 batteries for which ever drone, I might not use them all, but if I only take 3 and I need 4ā¦ I wonāt be a happy bunnyš
Some how I have managed to acquire 9 batteries. Consequently they very rarely all get used. As my flying session very rarely end up using more that 2 batteries I come back with the rest still fully charged. They slowly discharge over the next few days. I do keep a record in each of the battery storage pockets of when that battery was charged and to what level.
There are regular periods when I am unable to fly so as a precaution I will have a charging session when all batteries are charged to 100%. This is usually at two month intervals.
I do keep a very close eye open for any ābulgingā or unusual behavior.
To date I have had no issues. Some of the older batteries are now 5-6 years old I am not sure how old as I bought the whole rig second hand. Each battery is numbered and I am careful always to return it to its similarly numbered storage pocket. I never store a battery in the drone as they are always removed after a flight.
Flying Shroppie