Transferring £4000 out of S&S ISA to LISA account each year

My plan is to add £1000 to VUAG each month and then by the end of each financial year, sell £4000 and partial transfer it to my LISA on Money Box. I’ve read neither provider charge fees for this. I’ve seen on here that you should buy stocks and leave it for 5 years, so does my plan not work? If there’s no fees involved in this process then I can’t see any flaws? Advice would be appreciated