I think that to answer your questions and qualify the answers in a way that allows you to extract anything valuable would take quite an effort, so I'll link you to some information I'm certain will increase the rewards you get for your efforts at growing woody material in containers.

First, this is a copy/paste job of something I wrote about container size several years ago:

How
large a container ‘can’ or ‘should’ be, depends on the
relationship between the mass of the plant material you are working
with and your choice of soil. We often concern ourselves with
"over-potting" (using a container that is too large), but
"over-potting" is a term that arises from a lack of a basic
understanding about the relationship we will look at, which logically
determines appropriate container size.

It's
often parroted that you should only move up one container size when
"potting-up". The reasoning is, that when potting up to a
container more than one size larger, the soil will remain wet too
long and cause root rot issues, but it is the size/mass of the plant
material you are working with, and the physical properties of the
soil you choose that determines both the upper & lower limits of
appropriate container size - not a formulaic upward progression of
container sizes. In many cases, after root pruning a plant, it may
even be appropriate to step down a container size or two, but as you
will see, that also depends on the physical properties of the soil
you choose. It's not uncommon for me, after a repot/root-pruning to
pot in containers as small as 1/5 the size as that which the plant
had been growing in prior to the work.

Plants
grown in ‘slow’ (slow-draining/water-retentive) soils need to be
grown in containers with smaller soil volumes so that the plant can
use water quickly, allowing air to return to the soil before root
issues beyond impaired root function/metabolism become a limiting
factor. We know that the anaerobic (airless) conditions that
accompany soggy soils quickly kill fine roots and impair root
function/metabolism. We also know smaller soil volumes and the root
constriction that accompany them cause plants to both extend branches
and gain o/a mass much more slowly - a bane if rapid growth is the
goal - a boon if growth restriction and a compact plant are what you
have your sights set on.

Conversely,
rampant growth can be had by growing in very large containers and in
very fast soils where frequent watering and fertilizing is required -
so it's not that plants rebel at being potted into very large
containers per se, but rather, they rebel at being potted into very
large containers with a soil that is too slow and water-retentive.
This is a key point.

We
know that there is an inverse relationship between soil particle size
and the height of the perched water table (PWT) in containers. As
particle size increases, the height of the PWT decreases, until at
about a particle size of just under 1/8 inch, soils will no longer
hold perched water. If there is no perched water, the soil is ALWAYS
well aerated, even when the soil is at container capacity (fully
saturated).

So,
if you aim for a soil (like the gritty mix) composed primarily of
particles larger than 1/16", there is no upper limit to
container size, other than what you can practically manage. The lower
size limit will be determined by the soil volume's ability to allow
room for roots to ’run’ and to furnish water enough to sustain
the plant between irrigations. Bearing heavily on this ability is the
ratio of fine roots to coarse roots. It takes a minimum amount of
fine rootage to support the canopy under high water demand. If the
container is full of large roots, there may not be room for a
sufficient volume of the fine roots that do all the water/nutrient
delivery work and the coarse roots, too. You can grow a very large
plant in a very small container if the roots have been well managed
and the lion's share of the rootage is fine. You can also grow very
small plants, even seedlings, in very large containers if the soil is
fast (free-draining and well-aerated) enough that the soil holds no,
or very little perched water.

I
have just offered clear illustration why the oft repeated advice to
‘resist potting up more than one pot size at a time’, only
applies when using heavy, water-retentive soils. Those using
well-aerated soils are not bound by the same restrictions. As the ht
and volume of the perched water table are reduced, the potential for
negative effects associated with over-potting are diminished in a
direct relationship with the reduction - up to the point at which the
soil holds no (or an insignificant amount) of perched water and
over-potting pretty much becomes a non-issue.

This, about woody plants grown in pots for the long haul provides a good outline covering what's required to keep trees healthy for periods measured in decades instead of months.

Al

Thanks Al. You have given me a lot to think about. i had planned the 100L pot as its final "home" with the occasional re-potting just to re-juvinate the potting mix after some years.

100L will support a lot of tree if the roots are well managed. If roots aren't well managed, I could see 100L not being enough pot to the point of being significantly limiting within a 5-7 year span. Some will try to sell you on the idea that a tree NEEDS to be root bound to produce well in pots, but if that was true, the millions of in situ plants in our landscapes would all either be producing poorly or be producing well only for the reason some enterprising orchard manager figured out how to contain the roots of fruit trees so they grow in tight little knots directly under the trunk.

Al

I am assuming you are in Australia and so you should be close to your optimal time to repot. I would be interested in updates to this project. I have a mango tree that I grew from seed out of curiosity. It does not fruit obviously but it has flowered couple of times. Next year I am planning to buy a grafted mango tree and so my interest in updates on progress from you.