Difference of usage between 普通, 普段, 通常, 平常, 正常, いつも, and たいてい

Question

I'm curious about the nuances/differences between these words when used for the concept of "normal" or "usual." Every time I think I understand the difference between these, I get surprised when I still don't.

For example why are the following sentences ungrammatical/weird?

• あの店は、どんな果物でも普段売っている
• たいてい飲んでいる薬がありますか？

Edit: To maybe give a better example of why they overlap:

Example 1:

• 普段は夜８時まで営業しています
• 通常は夜８時まで営業しています
• 普通に夜８時まで営業しています
• 平常は夜８時まで営業しています

Example 2:

• 普通に戻す
• 通常に戻す
• 正常に戻す
• 普段に戻す

Example 3:

• 普段のところに行こう
• 通常のところに行こう
• 普通のところに行こう
• いつものところに行こう

Answer 1

The meaning of those words span over usually, always, generally, commonly, normally etc., depending on the context. The following is a random sketch of what comes to my mind. (I don't put links, but some are based on goo辞書)

Basic overlap

The overlapping meaning of those words is usual(ly).

Grammar

1. All are technically nouns.
2. 普通 and 通常 can be used as an adjective or as an adverb. (e.g. 普通電車, 通常使わない)
3. 正常 can be used as an adjective with or without な (e.g. 正常状態, 正常な状態) but not as an adverb.
4. 普段 is mostly used as an adverb.
5. 平常 is usually used as an adjective without な (e.g. 平常運行, not 平常な運行). 平常 is mostly used in specific combinations.
6. 正常 and 平常 are not natural with の (正常の状態 may be possible, but 平常の体温 is definitely weird).
7. いつもだ may be possible in speech (e.g. xxがxxxなのはいつもだし). いつも and たいてい are mostly used as an adverb.
8. When using with だ, it is more natural to use xx通りだ (except 正常).

	－as adj	－ as adv	な	だ	に	の
普通	〇	〇	△	〇	△～〇	〇
普段	－	〇	－	－	－	〇
通常	〇	〇	－	△	－	〇
平常	〇	－	－	△～〇	－	△
正常	〇	－	〇	〇	〇	△
いつも	－	〇	－	△	－	〇
たいてい	－	〇	－	－	－	〇

*〇=acceptable, △=maybe possible, －=not acceptable

Meaning

1. 普通 is an antonym of 特別. So, the meaning is more common, ordinary, average, and in some cases can be translated as usual.
2. 正常 is an antonym of 異常, normal=absence of abnormality. 平常 can be also translated as normal=as usual, as the thing is most of the time.
3. いつも is always and means usually in a relaxed sense. In the latter sense, it is not different from たいてい or 普段.
4. たいてい is most(ly). たいていのX implies a collection of most X.
5. 通常 overlaps with 普通 to some extent; 通常 is more formal; 通常 has some rules assumed (at least more so than 普通), and can be translated generally. The table below is from goo辞書.
6. 普通は vs 普通に. I think 普通に as an adverb (such as 普通におもしろい; or in Example 1) is a recent usage. The meaning of 普通におもしろい could be slightly different depending on context, but it means it is worth being called interesting, but may not very interesting (like, if it is used for a manga in some magazine, 普通におもしろい means it is interesting enough to read on, but may be not enough to buy). 普通は is more usual usually.

	…の方法	ごく…の人間	今日の彼は…じゃない	…の業務は五時まで
普通	○	○	○	－
通常	○	－	－	○

Comments on examples

1. Example 1: 平常は is not natural (Grammar 5). 通常は (and missing 普通は) can mean (a) generally and (b) usually (as an everyday fact). 普段は only means (b). 普通に is natural, but means more like there is nothing special about the shop, it is open until eight.
2. Example 2: 普段に is not natural (Grammar 4). The others mean mostly similar, it depends on what it is about. If it is about a broken machine, use 正常に; about train schedule, 通常に (from a special schedule over the holidays, for example); 普通に戻す can be used in most cases. Also note this 普通に is not an adverb, but simply 普通+に(to).
3. Example 3: 普段のところ and いつものところ mean the same: the place(s) we go quite often (たいていのところに行こう is not possible). 普通のところ means the place where there is nothing special/eccentric about=an average-looking place. 通常のところ would mean either, but sounds unnatural possibly due to the formal nature of 通常.

Answer 2

挙げられた二つの例文に関してのみですが：

あの店は、どんな果物でも普段たいてい売っている。

「たいてい」はもともと、頻度を表すものではなく、『ほとんどすべてに及ぶさま』や『確率が高いさま』を表します。この例文の「どんな果物でもたいてい売っている」も、「ほとんどすべての果物に及ぶさま」や「売っている確率が高いさま」を示しているものです。『頻度の高いさま』を表して「ほぼ毎日 (almost every day / on a daily basis / habitually) 売っている」と言いたいのではないので、「普段」で言い換えるとおかしいです。（「日曜はたいてい家にいます。」のような文では、時間的な割合や確率が高いさまを表して「日曜に家にいる確率が高い」という意味から、「たいてい」を "usually" の意味で使えます。）　

たいてい普段飲んでいる薬がありますか？

「たいてい」は『ほとんどすべてに及ぶさま』や『確率が高いさま』を表すので、この文には合いません。「日常的に・ほぼ毎日飲んでいる薬」と言いたいので、「普段」がいいです。

Answer 3

Not a complete answer but a few points from my experience:

いつも stands out in this list because it basically means 'all the time', which is a very absolute statement. My experience is that sensibilities in Japanese usage make this an unlikely choice.

普通 is often used to describe a normal type of 'thing' (local train, general bank account, standard vehicle vs 'kei' vehicle)

普段 gets used a lot to describe proper practice/behavior

Take heart. Even though I have had exposure to Japanese since 1989, I still find it difficult to know which words to use when.