>>21517245
Depends on how many you have to cut. It's probably just 8 in that pic and if that's all then it would 100% be slower to reach into your drawer of drink lids and sexual aids to pull out two plastic lids, then place them all in there, sandwich the second lid on top, and work the knife along the center-line. If you were teeing yourself up to do a couple dozen then sure, but you also need to make sure that you group them by similar sizes because smaller tomatoes will be cut unevenly compared to larger ones if you cut from the same vertical height.
Unless you're doing a shit-ton then it's more trouble than it's worth and you probably won't get cuts that are perfectly even like if you went individually.