Construction costs are currently skyrocketing

Yes, with rubble you simply reach the weight limit too quickly, insulation and wood very quickly reach the space limit. That's why I find an open flatbed so practical. With that, you can often go much further with wood and light building materials. I wouldn't call made-up hours overtime. Without my trust-based working time regulation, the construction wouldn't have worked out or would have become much more expensive. But I can also work well late in the evening, when everyone is already in bed, you can get a lot done or plan much more concentrated. During normal office hours, I'm almost always in meetings/calls anyway, and if there is a little time, it's spent answering questions and gathering information. But yes, that is individual and everyone has to consider it for themselves and then honestly assess it.

however, this is often solved by a smaller additional load so that it doesn't make too much of a difference.

Although that is at most cheating the customer and can cause serious trouble during inspections. Not all countries are as sensitive about overloading as Germany.

Doing it yourself is worthwhile, yes. But not if you waste time transporting material that the professionals can deliver in larger quantities much cheaper.

The question is always whether you have the larger quantities. For the garden shed foundation, I needed 20m of curbstones, paving slabs for 15 sqm, 2t of concrete gravel, 10 bags of cement, 10t of crushed stone, 1t of 2/5 grit, joint grit. You round 10t of crushed stone up to a three-axle truck and have it delivered. You can either buy joint grit as 2 bags or get a trailer full at the same price from the gravel plant. For curbstones, paving slabs, and cement, delivery by freight forwarder almost costs as much as the material. The same problem occurs with 2t of concrete gravel, because you always pay transport costs for the full truck at the gravel plant, regardless of how much you actually ordered.

As for the move, I've been taking boxes with me for a while when I go to the construction site. Currently, they are piling up in the garden shed; soon some can also go to the attic. The plan is that on the actual moving day, we only transport the furniture; one trip will be tight, but two trips should be quite enough. At 150 km, it looks different, it has to work with one trip.

Here in the Bavarian hinterland, a new construction project for a turnkey KFW40 semi-detached house with 158 m2 of living space and 450 m2 plot size has been listed today for €420,000, a carport with storage room would be available for an additional €25,000. This corresponds to about €2700/m2 including land, foundation, etc. If you assume €100/m2 for the land, then it is even only €2374/m2 for timber frame construction with a good standard...

Are these the first failed financings? There are also increasingly unfinished buildings for sale on the portals.

We still have great difficulties finding a suitable plot or a suitable existing property.

Does not have to be. They can also be divorce items, which have existed repeatedly in the past, only now they stay online longer and not every price is paid anymore.

(...)
The question is always whether you have the larger quantities. For the garden house foundation, I needed about 20m of curb stones, paving slabs for 15sqm, 2t of concrete gravel, 10 bags of cement, 10t of crushed stone, 1t of split 2/5, jointing sand. You round up 10t of crushed stone to a three-axle truck and have it delivered. You can either buy jointing sand in 2 bags or get a whole trailer load at the quarry for the same price. For curb stones, paving slabs and cement, delivery by freight forwarder costs almost as much as the material. The same problem with 2t of concrete gravel, because at the quarry you always pay transport costs for the full truck, no matter how much you actually ordered.

As for the move, I have been taking boxes with me for some time when I go to the construction site. Currently, they are piling up in the garden house, soon some can also go up to the attic. The plan is that on the actual moving day we will almost only transport the furniture; that will be tight with one trip, but quite certain to be enough with two. At 150km it's different of course, that has to work with one trip.

Did I claim otherwise? ;)
I gather from your answer that you had the 10t crushed stone delivered and did not drive back and forth 10 times with a trailer.

I just checked, for example, at Hornbach I can have 100 lawn edging stones delivered for 39.90 EUR because I live within a 20km radius of the store.
That's 1.8t just like that. Driving to the store, loading up, driving 2 times with a normal car/trailer… you have to have the trailer first… then driving 1-2 hours through city traffic…

And Hornbach delivers it to the curb at my property for 39.90… and that's supposed to not be worth it? ;)

You massively underestimate the value of your time, in my opinion. And also the costs of the car that you constantly move from A to B. I have a company car, that might still be worth it… but the time… the time…

PS:
This also works with 500 stones, so 9t.

I was just about to look for a comparison offer, but unfortunately Obi Mähwinkel only delivers in pallets of 77 pieces ;) Hornbach also charges me a hundred for delivery and takes 2 weeks. Well, I wouldn't drive there, since the nearest one is in Rottweil and that's quite far away ;)

City traffic

We don't have that, we live in the countryside.