Is つつ for formal or literary use only -- or not?

Question

I've found multiple sources instructing to use the つつ particle after the -masu stem of a verb only in formal or literary contexts. However, I sometimes find what appear to me to be contradictory examples.

Here's one from a source for JLPT training. It warns:

注意
・ 「～つつ」はformalなので「アイスクリームを食べつつ、歩いた」のような文には合わない。

But later gives this example sentence of correct usage: ⑥ あんまり無理すると倒れるよ。少しは休みつつやりなよ。

This sentence appears to me to occur in a casual, spoken conversation. What gives? Is つつ for formal/literary use only, or not?

Answer 1

I guess it is difficult to give a clear answer to a register question like this, but

• つつ can be used in speech;
• It is more likely to be used by grownups. At least I don't expect a small kid to use つつ.

Another factor might be a rhythm of the whole sentence or collocations, which I'm not really able to explain.

Two verbs that may be frequently heard with つつ would be 知る and 思う. For example,

• テスト勉強しなきゃと思いつつテレビ見ちゃう Whereas I know I have to work for exams, I always watch TV

may be used by a teenager.