Some toddlers grow quite fast and naturally, they tend to overgrow their clothes. Some parents are keen on the fitness aspect and buy clothes cut to size. I think it would make more sense to buy a cut above their size which translates into savings. For good measure, they should be easy to wash.
In my experience, yes, toddlers grow too fast that they leave behind their clothes. I remember my mother when buying clothes for my younger brother who was a toddler, she would bring me along in shopping to use me in measuring the clothes for my little brother. That's because the toddler can use that clothes for just a few months. At least if it is 2 sizes bigger then it can be used for at least a year. Those are tricks that we can inherit from our mother.
Though I don't buy clothes that are exactly fit, I don't buy extra large too, otherwise the shirt might keep falling down, especially when the collar is too large/wide. I usually buy T-shirts for my kids, so I buy those that are just comfortable to wear. Since I already planned to have a few kids, so I was fine to buy just comfortable ones for my eldest, and the other younger siblings just wear the old shirts. Moreover, I think my kids don't grow too fast, so they have been wearing the T-shirts for quite a long time.
I always buy one size larger for my son's clothes. Because as we all know, kids grow really fast and there is no sense in throwing away good clothes in just a few months. So buying at least one size bigger is a wise, economical method. Also, sometimes my son won't give up some clothes that are a bit small, especially T-shirts, so I let him wear it while playing and I don't have to bother much about stains or anything that do not wash away as he wears them only for playtime.
I agree that toddlers do grow up fast, and their clothes will go to waste if it will not fit in a few months. So it really is advisable to buy clothes 2 to 3 sizes bigger for the toddler to be able to use them for 2 years or more.
That's a good savings trick. An oversized clothes for the kid is practically recommended to cope with his fast growing up. My wife is very goid in estimating the sizes of clothes for our kids. I admire her mental alertness when we go shopping for our kids garments.
My niece who is a young mother bought one set of clothes for their toddler that will be for use until 2 years from now. But I said how did she estimate the size one year from now? That made her smile because it is not really good to buy clothes in advance. Just buy for now and next month you will get to know. At least she realized what I was saying.
I do believe that you don't need to buy a big amount of clothing for your little ones because they grow so fast.