9 week solo trip to Asia this year - Am I jumping around too much?

Hi everyone!

I'm looking for some advice on my current itinerary for a 9 week solo trip to Asia I'm going to be doing from October to December this year.

So this is my rough itinerary (open to change):

South Korea (Seoul & Buson)-> China (Beijing & Shanghai) -> Hong Kong (#1) -> Indonesia (Nusa Pineda/Gili Islands/Komodo) -> Hong Kong (#2) -> Thailand (Andaman coast & Bangkok) -> Saigon -> Phu Quoc -> Singapore -> home

Fly into Seoul Thurs 29th Oct

Fly Seoul to Beijing Friday 6th Nov

Fly Shanghai to Hong Kong Thurs 12th Nov

Fly Hong Kong to Indonesia Monday 16th Nov

Fly Indonesia to Hong Kong Friday 27th Nov

Fly Hong Kong to Thailand Monday 30th Nov

Fly Karbi/Phuket to Bangkok Monday 7th Dec

Fly Bangkok to Saigon Friday 11th Dec

Fly Saigon to Phu Quoc Monday 14th Dec

Fly Phu Quoc to Singapore Friday 18th Dec

Fly home 20th Dec

Couple of trip specific details (that add some constraints):

1. One of my good friends lives in Hong Kong, hence why it's on the itinerary twice. I want to get two weekends with them if I can. (Also, bonus will be that I can stay at their place)

2. Hong Kong can't be my final destination before going home as my friend will be out of the country.

3. My friend in Hong Kong said they'll also do a weekend in Saigon with me if that can be planned (so I've gone for my second last week)

4. I have another friend in Singapore who I'm thinking I'll visit on the final couple of days of my trip

5. I've tried to balance the itinerary between time in cities where it will be busier and more relaxed environments like on islands and by the beach

6. The sequence I've gone with is to suit the weather/ season in each region. Starting with the Korea/China part before it gets too cold. Then Indonesia before Monsoon season in December. And the weather should be good in Thailand and Vietnam from late Nov through December.

So my question is: am I trying to cover too much ground?

I'm think I'm pretty happy with the first leg of my trip (South Korea through to the first Hong Kong weekend).

There are 9 flights listed there traveling within Asia - across 53 days (and this doesn't include the long haul flights from/back home). My concern would be the amount of time travelling between places and becoming exhausted from it.

Have any of you done something like this before and what were your experiences?

For those of you who have backpacked for many months, do you book all of your flights well in advance or are you booking a lot of them last minute (within a couple of weeks)?

Thanks so much for your help and feedback!

EDIT: It's actually only 7.5 weeks but I can't update the title of this post.