It took time when I first went vegan because I didn't know that much. For example, I had to look up recipes every time I wanted to cook something new, I had to google everything I wanted to buy to make sure it's vegan and I had to spend a lot of time reading the ingredients off of everything. Now it doesn't really take any more time than I used to live before. I google things sometimes but honestly, that takes about 1 minute, and if I'm unsure or if I just can't be bothered googling I just email the company I want to buy something from.
Almost all animal products are allergens and needs to be clearly visible so I don't think it takes up any time. If you look at the ingredients on something containing animal products you'll see that stuff like milk, eggs etc are bolded. And I often buy stuff that says "vegan" on the package so.
I'm not vegan but I have made alot of vegetarian (not lakto-ovo-vegetariang but whats normally called vegan) food in my days. Mostly from scratch and I can get away with making a full meal in 10 min like potato and lentil soup is one of our favorites.
When it comes to vegetarian cooking it's like all cooking, you can make it difficult like making your own seitan and tofu, baking oall of your own bread etc etc or you can get away with less than 10 min cooking per meal.
I do both depending on my mood but then I love cooking