Mono is fine if you don't expose your hairline, and it does last longer than lace or skin systems since it's more durable. However, I think lace is better overall as it's lighter and less detectable. Depending on the density of hair you choose, you should be able to get at least 6 months from an all Swiss or French lace system if you look after it well. I've often had the same Swiss lace system for a year (due to supply shortages in the pandemic), though it's not necessarily ideal to have to make a system last that long.