I used to pack too much, however after my first trip to Europe many years ago, I realised I only wear the same few clothes all the time anyway, so generally pack about half what I used to.
Last time I went on a cruise however, I did the same -wore the same few clothes and could have packed far less but on a cruise I get worried that I cannot wear the same thing every night, but after one day at sea, I didnt care what I wore!
I used to be very organised and write lots of lists, planning outfits for every day I was away and working out exactly what other things I needed..... then I got older and more intolerant for time spent writing such lists! So now I just throw things in a suitcase and wear them or not as I see fit at the time. So sometimes it's too much and sometimes it's not enough but mostly I'm happy to say it works out just right!
I have always travelled light!! I have never worried about only taking a few sets of clothes.As long as I can hand wash my underwear at night,then I am a happy traveller!! I would rather take too little and have lots of space to fill with goodies found on the trip away from home!!
I've gradually decreased from the large amount I used to pack as it occurred to me that I can buy anything I need over in the other area I'm going to...and the less I pack, the more room there is for souvenirs!
As a former girl guide leader I learnt to pack light. I hand wash my underwear whilst travelling so only take 5 pairs even on a long trip, take light tops that don't need ironing, an umbrella and poncho, a warm jacket and 2 good outfits for dining, the bottoms of which I can also use for day wear, and small sized cosmetics packed in see-through plastic pouches or plastic bags. I use my toiletry bags on home soil as I tend to travel lightly with clothing here as well. But my husband is so different. Shoes for different outfits, clothes that need pressing mostly and a heck of a lot more that he doesn't need.