Top dressing soil

Yes and no, depending what you are top dressing with and how heavy the plant is feeding. I use dry amendments in my growing and I top dress my medium every 3 weeks and transplant every 5-6 weeks. Top dressing works by adding in whole things like feather meal, worm castings, bone/blood powders and literal shit for the microbes to break down and then freed your plants. It takes longer to feed to them but its also long lasting. Some items like guano and worm castings break down faster vs rock dusts and green sands. I use a product called Gaia Green and it works wonders. It needs a bit of love like extra Mg I find and a boost of microbes helps but over all a great product. Other brands like it are Down To Earth, Dr.Earth, Acti-Sol all amendments for the soil. You can also use slow release pellet fertilizers, these will not require as much though and does not matter if its grown in soil or hydro style mediums. The water only method is one I like a lot, It works for me and I find it simple. Others much prefer the control of what you feed every feed. and a great products for that is JACKS, its a three part feed, mix it all up and u got some good looking plants start to finish. Grated you a mixing up feed every time you water if you want to hand water. doing a reservoir is also an option but gotta keep it cool to prevent bad bacteria from growing in it, this is what they do in DWC style grows. Whatever you pick, lots of options on both sides of the coin. Good Luck!