The battery is happiest at 50% state of charge.. Yes, If you drain it to 30%, that's where you should leave it until you are ready to ride again. There's no reason to charge it up to 50% unless you plan to store it
You've been doing it right. It depends on the size of the battery and how much you intend to use on the ride. I have a large pack, 40Ah, so I have plenty of capacity without having to charge it fully for rides under 80 miles. To extend the battery's life, don't charge the pack past 85% capacity or discharge it past 20% capacity. If you need the full charge, top it off before the ride. Never charge it when it's near freezing, and don't let the pack sit charged for months on end.
Because you can only charge 100%, this will cut the number of recharge cycles by at least 1/3, more if you are depleting past a 20% charge. I charge my 58.8V packs to 85% capacity or 56.8V and never discharge past 20% capacity or 45.4V, about 75% of the time. If I plan on a long day, I finish charging from 56.8 to 58.8 volts just before leaving. If you are using the last 20% of your battery's capacity,, you need a larger, and another battery.
"Because you can only charge 100%, this will cut the number of recharge cycles by at least 1/3, more if you are depleting past a 20% charge. I charge my 58.8V packs to 85% capacity or 56.8V and never discharge past 20% capacity or 45.4V, about 75% of the time. If I plan on a long day, I finish charging from 56.8 to 58.8 volts just before leaving. If you are using the last 20% of your battery's capacity, you need a larger, and/or another battery." Again.