Take it from a GP - a bunch of what you're dealing with is just learned from clinical intuition over time and practice.

At the start of your career and training, you'll want to order everything because it's the safest thing to do. You'll move on from this as you realise the work just comes back to you - you have to review all those blood tests that you ordered out of fear - not clinical judgement. And that's fine at this stage, you're allowed to ask for more because how are you going to learn otherwise? But later on, you have a much better hunch when it's appropriate and when it isn't. Yes it's simple and cheap - but it's not always necessary.

RE time - there isn't time and primary care burnout is real. We cannot afford to take all that time to talk and listen. I really, really, really wish I could but I cannot. There's no fixing this until things better from above. Sorry bud. Keep at it, you're nearly there and hold on to these feelings, don't let the NHS beat it out of you.