you don't need to follow what battery percentage you have just make sure that do not let below 20%. but you top-up at any % like for example 45%-75%, 33%-63% and many more so at the same you can even do partial charging....like suppose you have 20% so even you can do 20%- 29%, 62%-68% and so on...but where as when if you plan to use your device long term and no need to go service centres then I will suggest you need to follow these steps and if you want to do 100% charge your device you then take once in a month to charge 100% you can regain original battery cell power if you want.
but some modification needed not always 70-80%, not fixed like that use till some time 20, sometimes 30 and charge upto sometimes 80,90,70. and atleast onnce in a month used 100-0 then charged upto 100
I have never bothered about charging and still my all mobiles never had any issues with battery. I used LG V30+ for 2 years 9 months and I mostly charged it to 100% and then drained it to 0%. Till now battery is working well, almost as good as when it was new.
So battery deterioration won't happen unless you keep charger plugged in overnight.
Otherwise during 2-3 years , you will hardly notice any difference.
Ideally you should follow Option 2 but don't worry too much about it. Only take care that you are not keeping mobile charger plugged in overnight , means despite being full charged.