most sealant in self sealing tubes are most often used in tubes that are not made using the most durable material when compared to a well known reliable & trusted brand. IMO, it'd be better to add sealant to a better quality & fitting tube. I also would not plan on most patch work to adhere to a sealant filled tube during a roadside repair.
I've worn enough T-Shirts to determine what is likely my experience when dealing with sealant, patches, tubes.
YMMV
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