patrick j wrote:

I am sure MK are quite right in their advice but I would be grateful if
someone would explain to me why soldered cable ends are a bad thing.

Because soft solder creeps under the compressive load of the screw,
resulting in a loose connection after a period of a few months or so.

Re-visit some of the ones you did earlier and the chances are that
you'll find that they're all loose.

MK are right; tinning the ends is very bad practice. If you want tidy
wire ends use crimped bootlace ferrules, or crimped ring terminals as
appropriate.

--
Andy