can one trunk chop in spring and then repot in summer on maples or is that too much for the tree?
I hold to the "one insult per year" rule steadfastly regardless of Repot time, especially with Repot.
Doing this with everything allows you to gain confidence in your repotting, without wondering if it was the "both" that did them in if they die.
This clarity is priceless. It may allow you to adapt more risky methods, like "saving bleeding" by doing both at once, but it, and a, almost excessive honor to patience because I uncovered the wolf in sheep's clothing that is impatience in bonsai, has me extending patience with this new concept which is so much more important than "aftercare".....
Prior Care!
I found an entire season of healthy unrestrained growth allows health enough for Repot and won't impede design with too much growth. Call this a 100 for the following....
Risk Assessment....
Give everything a "setback value".
Trunk chop.
A chop to bare is highly risky. (90)
A bud less risky. (60)
A branch with buds safest. (30)
Repot.
Bare root and heavy removal. (90)
Half removal. (60)
Slip pot. (30)
A chop and repot should always be considered 2 moves, with seperate goals for each, only combining them when you know each "setback value" doesn't exceed 100.
For me, a tree/trunk is only considered horticulturally at Repot time, except to ensure excess recovery growth doesn't impede design. The only idea is to set it up as horticulturally favorable as possible to regrow the roots, no risk setback values.
For me this includes a planned defoil on maple and prune to "trunk extension buds", these are the thick juicy ones that will grow most surely and most healthily, providing the most auxin to regrow roots.
Bud Values.
Fat trunk extension buds. (30)
Smaller side fill buds. (60)
Latent Buds or Nodes. (90)
These are the values that we must seek to "balance" on the top and bottom at Repot.
The year prior is used to get branches looking like this....
Then upon Repot, isolate the rootgrower sacrifice tips from the keeper fork, using this removal for "balance" as appropriate.

Then when the roots are refreshed, hit it at the yellow.
Of trunk chops.
I think it's most important to consider timing as such....
Chop in Summer when you need the activity reaction. (New lower branches)
Chop in winter when new low branches will impede design.
We are in control of wound care and healing regardless of time.
The only thing toying with our design is the amount of reaction to the chop.
Sorce