Is there an optimal placement for timing/frequency words?


I'm using Duolingo to supplement a 101 course I took and it doesn't really
explain that well where timing/frequency words should appear in a sentence.
For the sentence "I often play baseball with my older brother", Duolingo
defaults to the below answer:

**よく** 兄とやきゅうをします

Frequency word in bold. However, it also accepts a few others:

兄と **よく** やきゅうをします

兄とやきゅうを **よく** します

I don't know if these are correct, it's just what the app accepts as an
answer. Does it matter? In English there would be many ways to write that
sentence: "Often I play...", "I often play...", "I play often...". Is it
something like that perhaps?

I've noticed, though, that if there's a time word with the particle に, then it
will only accept an answer if it's in front, like in the sentence "I play
baseball with my older brother on Saturday":

**土曜日に** 兄とやきゅうをします

Why is it different here?




> [よく][兄と][野球を]します。

In this sentence, three segments I indicated with [] can be grammatically
placed in any order, though their nuance are slightly different.

> [土曜日に][兄と][野球を]します。

This is also the case when you change よく to 土曜日に. Duolingo sometimes fails to
judge your answer when there are variety of possible answers, but it's just a
Duolingo-specific problem, which you don't have to warry about in actual use.




> [よく][兄と][野球を]します。

In this sentence, three segments I indicated with [] can be grammatically
placed in any order, though their nuance are slightly different.

> [土曜日に][兄と][野球を]します。

This is also the case when you change よく to 土曜日に. Duolingo sometimes fails to
judge your answer when there are variety of possible answers, but it's just a
Duolingo-specific problem, which you don't have to warry about in actual use.

