It's recommended by PP.

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>It’s easy to use lube with condoms — just rub lube on the outside of the condom after you put it on. You can also add a few drops of lube inside the tip of the condom or on the penis before you roll the condom on. And you can put lube directly on a vulva and/or anus too. There’s no right or wrong amount — whatever feels good works.

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https://www.plannedparenthood.org/learn/ask-experts/how-do-you-use-lube-with-condom

and this handout:

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>You can apply a drop of lube inside the condom to increase sensations before you put on the condom.

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https://www.dshs.state.tx.us/hivstd/info/edmat/6-23.pdf

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Anecdotally, I've never had a condom just 'slip off' of a fully erect penis in 13 years of sex work. Breaks happen, and slippage can come when the blood leaves the party but an erect penis? Nah.