Macarons and what went wrong

Although previous attempt of making macarons has been successful, I later realized it was however not repeatable. Been trying to troubleshoot by different recipe, folding methods, oven temp adjustments, aged egg...whatever I could think of, I have tried. Including reading and reading all trouble shooting guide about macarons that bloggers and expert shared online. But still, success was not always with me...until I came across something new that I had never read of O_O . A new method of playing with oven temperature to bake those shells that I read from Butter,Flour & Me blog. I felt all hopeful again and my first trial result turns out like that......

Those were green tea macarons ...well I was jumping with joy when feet appear on all of the shells 5 minutes into baking and on both trays that I baked one after another.
Things I did to ensure success was
1. Using egg whites that is aged for 2 days
2. Beat egg white till stiff peak
3. Folding the batter and pressing out those air when the batter is ready and ensuring it is not over folded
4. Tip tap those shells after piping
5. Letting the shells rest for 30 mins till a shell forms
6. Follows exactly the oven temperature settings as instructed in the recipe

I was totally thrilled and damn excited...
Yet I was worried if it was repeatable or was it just pure luck.
Well, I was not totally contented as I did not know which factors contributed to my success and was this repeatable?

So.....here comes my repeat trial and I did some changes
1. Use fresh egg white that is at room temperature instead of aged egg white
2. Popping the shells into the oven without letting it sit to allow shell to form

Apart from the above, I follow the oven temperature steps diligently
Feet develop 5 mins into baking on all shells ^_^

As the original recipe and method is in Chinese, I had it translated to english for benefit of English readers :)

Original Macarons

Makes about 18 to 20 Macarons

Ingredients for Shells
A. Egg white at room temperature 45g, Fine Sugar 50g, Lemon juice Few drops (I omit this)
B. Almond Flour 65g, Icing Sugar 60g


Fillings
Nutella (I made my own chocolate genache)

Methods

1.  Using medium speed, beat egg white till formy, add lemon juice and half of the fine sugar
2. When soft peak begins to form, add rest of the sugar and beat at high speed till stiff peak
3. Meringue should be glossy and when you turn the bowl over, it will not drop
4. Sift in the dry ingredient B in 2 addition, folding gently with a spatula
5. Be careful not to overfold, batter should drop in ribbon stage yet not too runny
6. Press batter using spatula against mixing bowl to release air
7. Transfer batter into pipping bag, cut about 1cm hole at tip of bag
8. Pipe batter onto parchment paper *(I bang tray to release trap air after this step)
9. Allow shells to rest for 15-20mins to spread to its natural round
10. Preheat oven to 200degree C for 15mins, switch off oven and let tray sit in oven with oven door ajar with thick cloth for 3-5 minutes
11. Set oven to 140degree C and switch on oven, remove cloth from ajar oven door
12. Once feet develop (approximately 5 mins), adjust oven temperature to 120 degree C and bake for 3 mins
13. Adjust oven temperature to 100 degree C and bake for another 5 mins  *(I let the temp. stay at 120 degree c and bake till bottom of shells can be easily remove from parchment paper)
14. Leave shell to cool
15. Repeat from step 10 for the next tray of shells if applicable