sporadically

"You have twenty minutes to complete the test."

"The rains came late that year."

"I spent an hour at lunch."

"The irregulars attacked the government buildings, not following the standard military formations. "

"My sometimes neighbor, a retired teacher, still visits the school occasionally. "

"I stopped at the traffic lights."

"Due to the remote location, bus service to the town is infrequent. "

"The frequency of bus service has been improved from one every 15 to one every 12 minutes."

"The teacher explained the lesson thoroughly throughout the entire class period. "

"My sister is faster than I am; then, she is usually the first one to finish her homework. "

"The lumber company announced a large fell of trees in the forest this week. "

"My occasional helper at the bakery is a retired teacher. "