Actually no right or wrong of sending kids to those learning centres, just that some parents will prefer that as feeling kids are learning more compare to staying with parents and doing nothing much.
For myself, I feel it quite fun when I do activities with my kids at home. Just google some online info about Montessori home based activities and start planning it ahead and I find that my girl likes it very much and she enjoyed it. Saw a brochure about a centre charging for a school holiday program and its quite expensive which all those activities actually can be done at home with kids. So why not just plan ahead , perhaps plan together with the kiddo and I am sure they will find it very exciting! =)