I've tried both, and come to the conclusion that there exists a real risk of nuisance tripping when you have too small protected areas (as in single circuits) earth-fault-wise, especially if you're using grounded signal equipment like scopes and VTVMs. Or reasonably large sound systems. Therefore the entire panel is protected by a three-phase 40A RCCB. Main fuses are 20A so rating is no problem.
At least when a single circuit goes down it doesn't take any others with it. With an overall RCCB, everything goes off, and the trip current must be fairly high also, 100mA maybe?
Yes, it will trip everything, but since I am supposed to have an UPS on the annoying-to-trip parts, that's not an issue. Or should not be, if the UPS would do its job.
And the trip current is 30mA, which is the required value up to an upstream fuse rating of 63A -- above that you're not required to fit one; it should really come further downstream, implying another tier of sub-panels.
It tends to be earth leakage current with modern appliances that causes nuisance trips when there's no actual fault, though we've also found LED lighting to be a problem regarding inrush current; some MCBs/RCBOs have had to be uprated from 6A to 10A, though remaining type B (I have no say in this, my own preference would be to keep the current rating and go for a type C or D).
These breakers are a mix of 10 and 16A, C type. The EV charging outlet (strictly a preparation for something that has not happened yet) is fused 16A three-phase. Then there's a 16A single phase MK "Commando" style outlet (But, IIRC, ABB brand) , thought for a inverter type stick welder (also a prep plan), a 10A three-phase breaker for the workshop machinery that needs it, like lathe, air compressor, and drill press. These machines share a three-phase bus, but have individually tuned motor-protective relays. This bus also is fed through a contactor so that I have a central on/off switch and a convenient method for emergency stop.
Then, another pair of 16A Commando outlets, under the raised floor, to feed the computer rack with A / B mains buses, one being through UPS, one direct. Finally, 10A circuits for work benches and general use.
The electronic workshop bench has a separate circuit, and is also fed through the contactor arrangement, but on a separate contactor that can be overrridden into manual on (still protected by emergency stop) if I don't feel like running the air compressor.