I have taught both standard 45-50 minute periods and 90-100 minute block periods and this answer will cover my general structuring for both.
In general, I will always start off with a "warm-up" (review problem usually, but sometimes a video, image, etc), which lasts 5 minutes for standard periods. I then review any homework questions which can take anywhere from 5 minutes to nearly an entire period. It is important to continually think about the skill level of your students and the difficulty of the homework when planning for the next day's homework review time. If you assign 1-100 odds, be prepared for a lot of questions taking a lot of time, whereas if you assign 3, 5, and 6, then five minutes is probability a safe bet. In general, I usually allocate about 10 minutes to homework review, leaving 30ish minutes left for my core lesson.
I structure lessons in what I call "chunks" which last roughly 10 minutes each for a standard period. A chunk is an isolated cycle of introduce-example-practice-review. So for instance, when teaching a new theorem in Geometry, the first two minutes would be for introducing the theorem, possibly walking through a proof if it was basic enough. Then I would work an example problem for about three minutes on the board. Students are then presented with two example problems to work on for three minutes independently or in groups and then we review the problems in the last two minutes of the chunk. Then in the next chunk we repeat the same process but for either a more advanced application of the concept, a related concept, or even the same concept if it is more essential and deserves extra time.
I can usually fit in two ten-minute chunks for a standard period (45-50 minutes). The last 10-15 minutes of a standard period are spent on mixed practice of the material covered in the two chunks. Sometimes I will do examples on the board, have students present their solutions, discuss specific solutions in-depth, or any other number of things but this last section of class is always spent reinforcing the topics introduced in that lesson. I will usually end the standard period class with a 1 or 2 minute "exit ticket" which is usually a question such as "What is one thing you have learned today?" or "The sum of the interior angles of a triangle is __________________"
I structure block periods (90-45 minutes) slightly differently. In the district I teach and I'm sure many others, block periods are either done on a semester basis or on an every-other-day basis, so in either sense you only see students on half of the amount of days. While it is theoretically the exact same amount of time as standard periods meeting everyday, anyone who has taught blocks knows that the time is much different than in a standard period. Because of this I tend to follow the same general structure of a standard period, except that I go more in-depth during each phase of the lesson and thus spend more time in each phase. The warm-up will typically last 10 minutes, and will have either more problems than a standard period warm up or more in-depth problems for the students to work on. Homework goes the same as it did for standard periods, however I typically assume 20 minutes for review as I almost always assign more homework to block classes. I still do two chunks, however each chunk lasts roughly seventeen minutes. Four minutes for introduction of topic, 5 minutes for example, 5 minutes for independent work, and 3 minutes for review. This leaves roughly 30-40 minutes left in the period. I will usually give a 5 minute break in the middle of the period and when students come back we will essentially do the same thing as for the standard period, use the last portion of class reinforcing the topics that were introduced earlier. Spend roughly 25 minutes on a mixture of independent, group, and class work. One benefit of blocked periods is that you do have more time for activities and explorations because this last portion of the period is twice the length as a standard period. Because of the length of the period, I end block periods with a more formal exit-ticket, usually two problems that test a basic understanding of the material in the lesson and this takes roughly 5 minutes.
As with everything in teaching, this structure needs to be flexible, which is fine, provided that you have already anticipated many of the "pitfalls", "time sinks" and "rabbit holes". If your students were having a tough time with the previous day's material, you will probably want to allocate more time to review in the front half of the class, maybe making one chunk a review chunk. If there is an activity that you would like to do make sure you allocate enough time to complete it and discuss, possibly eliminating one of the two chunks. If you are introducing a lot of smaller but related concepts, doing three or four chunks in a period is not unheard of.
I would say that I stick to this general structure roughly 85% of the time. The other 15% of the time, will usually be spent on an activity or exploration that takes thirty or more minutes or on summative assessments. Prior to a test, I will usually spend an entire period reviewing and answering any questions that students have. Tests will almost always take an entire period. For block periods, I will use the first 45 minutes of class for review and the last 45 to take the test. For quizzes, it depends. Roughly half the time, I will have them in the beginning of class, when I am not anticipating too much struggling and there is content that I would like to cover afterwards. The other half of the time I will do quizzes at the end of the period, either because they are a quiz on what was learned in the first half of the period or because I feel that I need to review certain things before the assessment is administered.