A number of seeds down one hole

It is counter productive. They will compete with one another and you may end up with sickly seedlings, if any, which won’t survive.

If more than one germinates, you can always tease the other(s) out and replant elsewhere if they seem strong enough - althoughtt not all seedings take to being transplanted.

Thinning out is a necessary part of vegetable growing to give each plant a space to grow. Take out the weakest seedlings.

I haven't thinned out my seeds in the same way in recent years following something someone said on Gardeners World.

They said thinning by pricking/teasing out disturbs the roots of the plants you want to stay in place and the best way is to nip/cut the extra seedlings off at soil level if you've sown too thickly.

In my experience it does result in more vigorous plants.

What sort of seeds have you sown? Sweet peas? Nasturtiums? Lettuce? Sunflowers? etc.
Did you read the packet? The producers want you to get the best results possible with their product - so do as they suggest.

It’s a bit too early to plant most seeds outside just now, I’ve got them in cold frames and windowsills at the moment. It’s fine to plant more seeds than you need, as long as you pull out the weaker ones when they have germinated to give the others the best chance. I snip them off, so I don’t disturb the roots of the ones I want to keep.

I also would wait to plant seeds outside until the frosts are finished .
I'm longing to plant my gladioli out ,but a cold snap is expected .

Where I live on the south coast it is advised that most seedlings should stay sheltered or inside until sometime in May depending on the weather. Some people leave them out during the day and bring them in at night a few time to harden them off before planting out. You need to allow the soil to warm up a bit before replanting.

I’ve planted 2 or 3 before, and have quickly removed the last to germinate/the least robust-looking. Mind you I’m not growing loads of veg, just e.g. sweet peas, tomatoes or zinnias for pots or a small garden bed.