'A lot (of)' is usually preferable to 'much' in an affirmative sentence.
Yes, 'much' is also used in affirmative sentences, but it sounds awkward in yours -- especially since you used 'much' to modify a verb. In your sentences 'much' is used similarly to an adverb of frequency. So, it would sound more natural to use either 'a lot' or a word such as 'often'.
Student or Learner